Vehicle driving control method and vehicle driving control device

Abstract

To provide a vehicular travel control method and a vehicular travel control device each of which enables reduction of a mechanical load upon an emergency stop, thereby enabling a vehicle-stopped state to be maintained.SOLUTION: When an abnormality state of a brake control device 20 is detected, deceleration of an own vehicle V1 is started, and after an output value of wheel speed or an output value of an output rotary shaft has reached 0, a shift range of a speed change gear 182 is set to a parking position without using a hydraulic friction brake.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present invention relates to a vehicle driving control method and a vehicle driving control device. [Background technology]

[0002] In an autonomous vehicle, an on-board brake system is known that brakes the wheels using an accumulator actuator that supplies hydraulic pressure to a brake unit by releasing hydraulic fluid stored in a pre-pressurized state when an emergency stop switch is pressed (Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2021-006442 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, continuing to brake the vehicle using hydraulic brakes during an emergency stop places a large mechanical load on the vehicle.

[0005] An object of the present invention is to provide a vehicle driving control method and a vehicle driving control device that can reduce the mechanical load during an emergency stop and maintain the vehicle stopped state. [Means for solving the problem]

[0006] The present invention solves the above problem by starting to decelerate the vehicle when an abnormal state of the braking control device is detected, and after the output value of the wheel speed or the output value of the output shaft becomes zero, setting the shift range of the transmission to the parking position without using the hydraulic friction brake. Effect of the Invention

[0007] According to the present invention, the mechanical load can be reduced during an emergency stop, and the vehicle can be maintained in a stopped state. [Brief description of the drawings]

[0008] [Figure 1] 1 is a block diagram showing an embodiment of a vehicle cruise control device according to the present invention; [Diagram 2] 2 is a front view showing a part of the input device of FIG. 1. [Diagram 3] 2 is a plan view showing an example of lane change control of the driving control device of FIG. 1. [Figure 4] 2 is a block diagram showing an example of a braking control device included in the driving control device of FIG. 1. [Diagram 5] 5 is a plan view showing an example of braking control executed by the braking control device of FIG. 4. FIG. [Figure 6] 5 is a flowchart showing an example of processing executed by the braking control device of FIG. 4. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Configuration of the driving control device Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a block diagram showing the configuration of a vehicle cruise control device 1 according to this embodiment. The cruise control device 1 of this embodiment is also an embodiment for carrying out a vehicle cruise control method according to the present invention.

[0010] 1, the driving control device 1 of this embodiment includes a sensor 11, a vehicle position detection device 12, a map database 13, an in-vehicle device 14, a navigation device 15, a presentation device 16, an input device 17, a drive control device 18a, a steering control device 18b, a control device 19, and a braking control device 20. These devices are connected, for example, by a CAN (Controller Area Network) or other in-vehicle LAN, and can transmit and receive information to and from each other.

[0011] The sensor 11 detects the traveling state of the vehicle. For example, the sensor 11 may be a front camera that captures an image in front of the vehicle, a side camera that captures an image of the left and right sides of the vehicle, a rear camera that captures an image of the rear of the vehicle, a front radar that detects an obstacle in front of the vehicle, a rear radar that detects an obstacle behind the vehicle, a side radar that detects an obstacle on the left and right sides of the vehicle, a vehicle speed sensor that detects the vehicle speed of the vehicle, a touch sensor (capacitive sensor) that detects whether the driver is holding the steering wheel, and an in-vehicle camera that captures an image of the driver. The sensor 11 may be configured to use one of the above-mentioned multiple sensors, or may be configured to use a combination of two or more types of sensors. The detection result of the sensor 11 is output to the control device 19 at a predetermined time interval.

[0012] The vehicle position detection device 12 includes a GPS unit, a gyro sensor, a vehicle speed sensor, etc. The vehicle position detection device 12 detects radio waves transmitted from a plurality of satellite communications by the GPS unit, and periodically acquires the position information of the vehicle. The vehicle position detection device 12 also detects the current position of the vehicle based on the acquired vehicle position information, angle change information acquired from the gyro sensor, and vehicle speed acquired from the vehicle speed sensor. The vehicle position information detected by the vehicle position detection device 12 is output to the control device 19 at predetermined time intervals.

[0013] The map database 13 is a memory that stores three-dimensional high-precision map information including position information of various facilities and specific points and is accessible from the control device 19. The three-dimensional high-precision map information is three-dimensional map information based on road shapes detected when an actual road is traveled using a data acquisition vehicle. The three-dimensional high-precision map information is map information in which detailed and highly accurate position information such as curved roads and the magnitude of the curve (e.g., curvature or curvature radius), junctions, branching points, toll gates, and positions where the number of lanes decreases is associated as three-dimensional information along with the map information. However, the map information stored in the map database of the present invention is not limited to only three-dimensional high-precision map information, and may be other map information.

[0014] The in-vehicle devices 14 are various devices mounted on the vehicle and are operated by the driver. Examples of such in-vehicle devices include a steering wheel, an accelerator pedal, a brake pedal, a turn signal, wipers, lights, a horn, and other specific switches. When the in-vehicle devices 14 are operated by the driver, they output operation information to the control device 19.

[0015] The navigation device 15 acquires the current position information of the vehicle from the vehicle position detection device 12, and displays the vehicle's position on a display or the like by superimposing it on map information for guidance. The navigation device 15 also has a navigation function that, when the driver inputs a destination, calculates a route to the destination and guides the driver along the set route. With this navigation function, the navigation device 15 displays the route to the destination on the map on the display, and notifies the driver of recommended driving behavior along the route by voice or the like.

[0016] The presentation device 16 includes various displays such as a display provided in the navigation device 15, a display built into a rearview mirror, a display built into a meter section, a head-up display projected on the windshield, etc. The presentation device 16 also includes devices other than displays such as a speaker of an audio device, a seat device with a vibrator embedded therein, etc. The presentation device 16 notifies the driver of various presentation information according to the control of the control device 19.

[0017] The input device 17 is, for example, a button switch that allows input by manual operation by the driver, a touch panel arranged on a display screen, or a microphone that allows input by the driver's voice. In this embodiment, the driver can input setting information for the presentation information presented by the presentation device 16 by operating the input device 17. Fig. 2 is a front view showing a part of the input device 17 of this embodiment, and shows an example consisting of a group of button switches arranged on the spokes of a steering wheel, etc.

[0018] The illustrated input device 17 is a button switch used to set ON / OFF, etc., of the autonomous driving control function (autonomous speed control function and autonomous steering control function) equipped in the control device 19. Details of the autonomous driving control function including the autonomous speed control function and the autonomous steering control function will be described later. The input device 17 of this embodiment includes a main switch 171, a resume / accelerate switch 172, a set / coast switch 173, a cancel switch 174, a vehicle distance adjustment switch 175, and a lane change assist switch 176.

[0019] The main switch 171 is a switch for turning on / off the power supply of the system that realizes the autonomous speed control function and the autonomous steering control function of the control device 19. The resume / accelerate switch 172 is a switch for performing a resume operation such as restarting the autonomous speed control function at the set speed before turning off the autonomous speed control function once and then turning it off, or restarting the autonomous speed control function by the control device 19 after following a preceding vehicle (another vehicle traveling ahead in the same lane as the host vehicle. The same applies hereinafter in this specification) and accelerating the set speed. The set / coast switch 173 is a switch for performing a set operation to start the autonomous speed control function at the traveling speed and a coast operation to lower the set speed. The cancel switch 174 is a switch for turning off the autonomous speed control function. The vehicle distance adjustment switch 175 is a switch for setting the vehicle distance from the preceding vehicle, and is a switch for selecting one of multiple settings such as short distance, medium distance, and long distance. The lane change assistance switch 176 is a switch for accepting the start of a lane change when the control device 19 confirms with the driver that the lane change will be started. After accepting the start of a lane change, the lane change assistance switch 176 can be pressed for longer than a predetermined time to cancel the acceptance of the lane change suggestion made by the control device 19.

[0020] In addition to the button switches shown in FIG. 2, a turn signal lever of a turn signal or other switches of the in-vehicle device 14 can be used as the input device 17. For example, when the control device 19 suggests whether or not to change lanes by autonomous control, the driver can turn on the turn signal switch to input consent or permission to the lane change. Also, when the control device 19 suggests whether or not to change lanes by autonomous control, the driver can operate the turn signal lever to change lanes in the direction in which the turn signal lever is operated, rather than the proposed lane change. The setting information input by the input device 17 is output to the control device 19.

[0021] The drive control device 18a controls the running of the host vehicle in various ways. For example, when the host vehicle runs at a constant speed at a set speed by the autonomous speed control function, the drive control device 18a controls the operation of the drive mechanism (including the operation of the internal combustion engine in an engine vehicle, the operation of the driving motor in an electric vehicle system, and the torque distribution between the internal combustion engine and the driving motor in a hybrid vehicle) and the brake operation in order to accelerate and decelerate the host vehicle to the set speed and maintain the running speed. In addition, when the host vehicle runs following a preceding vehicle by the autonomous speed control function, the drive control device 18a controls the operation of the drive mechanism and the brake operation to realize the acceleration / deceleration and running speed so that the distance between the host vehicle and the preceding vehicle is constant.

[0022] Moreover, the steering control device 18b performs steering control of the host vehicle by controlling the operation of the steering actuator in addition to the operation control of the drive mechanism and the brake by the autonomous steering control function. For example, when the steering control device 18b performs lane keeping control by the autonomous steering control function, it detects lane markers of the host lane (the lane in which the host vehicle runs; the same applies hereinafter in the present specification) and controls the running position of the host vehicle in the width direction so that the host vehicle runs at a predetermined position within the host lane. Moreover, when the steering control device 18b performs lane change assistance by the lane change assistance function described later, it controls the running position of the host vehicle in the width direction so that the host vehicle changes lanes. Furthermore, when the steering control device 18b performs right / left turn assistance by the autonomous steering control function, it performs running control to turn right or left at an intersection or the like. The steering control device 18b controls the running of the host vehicle by instructions from the control device 19 described later. Moreover, other known methods can be used as a running control method by the steering control device 18b.

[0023] The control device 19 includes a ROM (Read Only Memory) that stores a program for controlling the traveling of the vehicle, a CPU (Central Processing Unit) that executes the program stored in the ROM, and a RAM (Random Access Memory) that functions as an accessible storage device. Note that, as the operating circuit, an MPU (Micro Processing Unit), a DSP (Digital Signal Processor), an ASIC (Application Specific Integrated Circuit), an FPGA (Field Programmable Gate Array), etc. can be used instead of or in addition to the CPU (Central Processing Unit).

[0024] <Functions realized by the control device 19> The control device 19 executes a program stored in the ROM by the CPU, thereby realizing a driving information acquisition function for acquiring information about the driving state of the vehicle, a driving scene determination function for determining the driving scene of the vehicle, and an autonomous driving control function for autonomously controlling the driving speed and / or steering of the vehicle. Each function of the control device 19 will be described below.

[0025] The driving information acquisition function of the control device 19 is a function for the control device 19 to acquire driving information related to the driving state of the vehicle. For example, the control device 19 acquires image information of the outside of the vehicle captured by the front camera, rear camera, and side camera of the sensor 11 as driving information. The control device 19 also acquires detection results by the front radar, rear radar, and side radar as driving information. Furthermore, the control device 19 acquires vehicle speed information of the vehicle detected by the vehicle speed sensor of the sensor 11, attitude angle and yaw rate of the vehicle detected by a gyro sensor, image information of the driver's face captured by an in-vehicle camera, and the like as driving information.

[0026] Furthermore, the control device 19 acquires current position information of the vehicle as driving information from the vehicle position detection device 12. The control device 19 also acquires a set destination and a route to the destination as driving information from the navigation device 15. The control device 19 also acquires position information such as curved roads and the magnitude of the curve (e.g., curvature or curvature radius), merging points, branching points, toll booths, and positions where the number of lanes is reduced as driving information from the map database 13. In addition, the control device 19 acquires operation information of the in-vehicle device 14 by the driver from the in-vehicle device 14 as driving information. The above is the driving information acquisition function realized by the control device 19.

[0027] The driving scene determination function of the control device 19 is a function for determining the driving scene in which the host vehicle is traveling by referring to a table stored in the ROM of the control device 19. In the table stored in the ROM of the control device 19, driving scenes suitable for, for example, lane changing and overtaking and their determination conditions are stored for each driving scene. The control device 19 refers to the table stored in the ROM to determine whether the driving scene of the host vehicle is suitable for, for example, lane changing and overtaking.

[0028] For example, four conditions are set as conditions for determining a "scene of catching up with a preceding vehicle", namely, "there is a preceding vehicle ahead", "the speed of the preceding vehicle is less than the set speed of the vehicle", "the vehicle reaches the preceding vehicle within a predetermined time", and "the direction of lane change does not meet the lane change prohibition condition". In this case, the control device 19 determines whether the host vehicle satisfies the above conditions based on, for example, the detection results of the front camera and the front radar included in the sensor 11, the vehicle speed of the host vehicle detected by the vehicle speed sensor, and the position information of the host vehicle by the host vehicle position detection device 12. If the above conditions are satisfied, the control device 19 determines that the host vehicle is in a "scene of catching up with a preceding vehicle". The above is the driving scene determination function realized by the control device 19.

[0029] The autonomous driving control function of the control device 19 is a function for the control device 19 to autonomously control the driving of the vehicle without relying on the driver's operation. The autonomous driving control function of the control device 19 includes an autonomous speed control function that autonomously controls the driving speed of the vehicle and an autonomous steering control function that autonomously controls the steering of the vehicle. Note that autonomous control without relying on the driver's operation also includes the driver performing some operations. In addition, the autonomous speed control function and the autonomous steering control function may be functions independent of each other, or may be functions related to each other. The autonomous speed control function and the autonomous steering control function of this embodiment will be described below.

[0030] The autonomous speed control function is a function that, when a preceding vehicle is detected, follows the preceding vehicle while controlling the vehicle distance so as to maintain a vehicle distance according to the vehicle speed with the vehicle speed set by the driver as the upper limit, and when a preceding vehicle is not detected, drives at a constant speed at the vehicle speed set by the driver. The former is also called vehicle distance control, and the latter is called constant speed control. The autonomous speed control function may include a function that detects the speed limit of the road being traveled from a road sign by the sensor 11, or obtains the speed limit from the map information in the map database 13, and automatically sets the speed limit to the set vehicle speed.

[0031] To activate the autonomous speed control function, the driver first operates the resume / accelerate switch 172 or the set / coast switch 173 of the input device 17 shown in FIG. 2 to input a desired driving speed. For example, if the driver presses the set / coast switch 173 while the vehicle is traveling at 70 km / h, the current driving speed is set as is. However, if the driver's desired speed is 80 km / h, the driver can press the resume / accelerate switch 172 multiple times to increase the set speed. The "+" mark on the resume / accelerate switch 172 indicates that the switch increases the set value. Conversely, if the driver's desired speed is 60 km / h, the driver can press the set / coast switch 173 multiple times to decrease the set speed. The "-" mark on the set / coast switch 173 indicates that the switch decreases the set value. The driver can adjust the desired distance by operating the distance adjustment switch 175 of the input device 17 shown in FIG. 2, and can select one of a number of settings, such as short distance, medium distance, or long distance.

[0032] Constant speed control, which drives the vehicle at a constant speed set by the driver, is executed when the forward radar of the sensor 11 or the like detects that there is no preceding vehicle ahead in the vehicle's own lane. In constant speed control, the drive control device 18a controls the operation of the drive mechanisms such as the engine and brakes while feeding back vehicle speed data from the vehicle speed sensor so as to maintain the set driving speed.

[0033] The vehicle distance control, which follows the preceding vehicle while performing the vehicle distance control, is executed when the forward radar of the sensor 11 detects the presence of a preceding vehicle ahead of the vehicle in the vehicle's lane. In the vehicle distance control, the drive control device 18a controls the operation of the drive mechanism such as the engine and the brake while feeding back the vehicle distance data detected by the forward radar so as to maintain the set vehicle distance with the set travel speed as the upper limit. If the preceding vehicle stops while traveling under the vehicle distance control, the vehicle stops following the preceding vehicle. If the preceding vehicle starts to move within, for example, 30 seconds after the vehicle stops, the vehicle also starts to move and starts to follow the preceding vehicle under the vehicle distance control again. If the vehicle stops for more than 30 seconds, the vehicle does not start automatically even if the preceding vehicle starts to move, and if the resume / accelerate switch 172 is pressed or the accelerator pedal is depressed after the preceding vehicle starts to move, the vehicle starts to follow the preceding vehicle under the vehicle distance control again.

[0034] On the other hand, the autonomous steering control function is a function for controlling the operation of the steering actuator to execute steering control of the vehicle. The autonomous steering control function of this embodiment includes: (1) a lane keeping function (lane width direction maintaining function) that controls the steering to drive, for example, near the center of the lane and assists the driver in steering operation; (2) a lane change assist function that controls the steering when the driver operates the turn signal lever and assists the steering operation required for lane change; (3) an overtaking assist function that, when a vehicle slower than a set vehicle speed is detected ahead, asks the driver through a display whether to perform an overtaking operation, and when the driver operates an acceptance switch, controls the steering and assists the overtaking operation; and (4) a route driving assist function that, when the driver has set a destination in a navigation device or the like, asks the driver through a display whether to perform a lane change when the lane change point required for driving according to the route is reached, and controls the steering and assists the lane change when the driver operates an acceptance switch. When autonomous steering control is executed, autonomous speed control is also executed at the same time, but speed control may be executed by the driver's accelerator / brake operation.

[0035] Here, the lane change assist function of the autonomous steering control function will be described. In addition to the lane change assist, autonomous speed control is also executed at the same time. FIG. 3 is a plan view showing an example of lane change control (lane change assist function) executed by the control device 19 of this embodiment. As shown in FIG. 3, when the driver operates the turn signal lever of the vehicle V1, the control device 19 turns on the turn signal, and starts the lane change operation LCP (Lane Change Process, which refers to a series of processes for autonomous lane change) when a preset lane change start condition is satisfied. The control device 19 judges whether the lane change start condition is satisfied based on various driving information acquired by the sensor 11. The lane change start condition is not particularly limited, but may be exemplified as follows: (1) lane keeping mode, (2) the driver is holding the steering wheel, (3) the vehicle is traveling at a speed of 60 km / h or more, (4) there is a lane in the direction of lane change, (5) there is space in the lane to which the lane is to be changed for lane change, (6) the type of lane marker indicates that lane change is possible, (7) the curvature radius of the road is 250 m or more, and (8) the driver has operated the turn signal lever within 1 second. Note that when the control device 19 determines that the lane change start condition is met by the lane change assistance function, even without the driver's instruction, it may suggest to the driver to change lanes by notifying the driver through the presentation device 16.

[0036] When the lane change start condition is satisfied, the control device 19 starts a lane change operation LCP. As shown in FIG. 3, the lane change operation LCP of this embodiment includes a lateral movement in which the vehicle V1 moves in the lane L1 toward the adjacent lane L2, and a lane change manipulation (LCM) in which the vehicle V1 moves from the lane L1 to the adjacent lane L2 across a lane marker. While the lane change operation LCP is being performed, the control device 19 presents information indicating that the lane change is being performed by autonomous control to the driver via the presentation device 16, and calls for the driver to pay attention to the surroundings. When the lane change maneuver LCM is completed, the control device 19 turns off the direction indicator and starts execution of a lane keeping function in the adjacent lane L2. In addition, the lane change operation LCP refers to the period from when the turn signal is turned on to when it is turned off by operating the turn signal lever, and the lane change maneuver LCM refers to the period from when the vehicle V1 starts to step on the boundary line between the vehicle's own lane L1 and the adjacent lane L2 to when it finishes stepping on it.

[0037] Now, when the vehicle is autonomously traveling using the autonomous driving control function, an emergency stop may be required due to a control malfunction caused by a system malfunction or the driver may be unable to operate the vehicle. The prior art documents cited in the prior art documents describe braking the wheels using an accumulator actuator that supplies hydraulic pressure to a brake unit by releasing hydraulic fluid stored in a pressurized state in advance when an emergency stop switch is pressed. However, braking the vehicle continuously using hydraulic brakes places a large mechanical load, making it difficult to continuously maintain a stopped state. Therefore, it is common to maintain a stopped state using an electric parking brake (hereinafter also simply referred to as a parking brake) after decelerating using a hydraulic friction brake. However, if the parking brake is not available, such a means cannot be used.

[0038] Therefore, in the vehicle driving control device 1 according to this embodiment, when an abnormal state such as a breakdown of the parking brake or a loss of an input signal from a system that controls the parking brake is detected, the host vehicle is first decelerated. This deceleration of the host vehicle can be performed using a hydraulic friction brake, and can also be performed using an engine brake and / or a regenerative brake of a driving motor instead of or in addition to the hydraulic friction brake. In the following, an example in which a hydraulic friction brake is applied to decelerate the host vehicle will be described. After the host vehicle is decelerated, if it is determined that the output value of the wheel speed or the output value of the output rotating shaft detected by the sensor is 0, that is, the vehicle is in a stopped state where the vehicle speed is not detected, the shift range of the transmission is set to the parking position. Hereinafter, an embodiment of the braking control using the braking control device 20 will be described with reference to FIG. 4 and FIG. 5.

[0039] Fig. 4 is a block diagram showing an outline of the brake control device 20 according to the embodiment of the present invention shown in Fig. 1. As shown in Fig. 4, the brake control device 20 of this embodiment includes an Assisted and Automated Driving Control (ADC) unit 21, a Vehicle Dynamics Control (VDC) unit 22, and an Emergency Brake Assist (EBA) unit 23, into which a signal or information is read from an output rotating shaft sensor 181 as the drive control device 18a, and a final command value is output to the VDC unit 22, the EBA unit 23, and the transmission 182. The VDC unit 22 corresponds to an example of the first brake control device of the present invention, and the EBA unit 23 corresponds to the second brake control device.

[0040] The ADC unit 21 executes control for driving assistance and autonomous driving of the vehicle. The ADC unit 21 realizes drive control function and brake control function by executing a program stored in the ROM of the controller by the CPU. The ADC unit 21 reads the driver's required drive force from the accelerator pedal sensor as the sensor 11 and the required braking force from the brake pedal sensor, and detects the current vehicle speed from the vehicle speed sensor to monitor the vehicle state, and outputs command values ​​according to these states to each device of the drive control device 18a and the brake control device 20.

[0041] The VDC unit 22 includes a VDCCU 221, a wheel speed sensor 222, and an electric parking brake 223, and constitutes a main system control unit of the brake control device 20. The EBA unit 23 includes an EBACU 231 and a wheel speed sensor 232, and constitutes a sub system control unit that backs up the main system control unit. Brake control during normal operation is mainly performed by the VDC unit 22 of the main system control unit controlling the electric parking brake 223 and the EBA unit 23 based on signals and information from the ADC unit 21. However, when an abnormal state is detected in the VDC unit 22, braking control can be performed using only the EBA unit 23 of the sub system control unit, and when an abnormal state is detected in the EBA unit 23, braking control can be performed using only the VDC unit 22 of the main system control unit.

[0042] The ADC unit 21 also has an emergency stop control function. Specifically, when an abnormality such as a failure or a system error of each device provided in the VDC unit 22 or the EBA unit 23 is detected, an emergency stop control MRM (Minimum Risk Maneuver) is activated to execute emergency stop control of the vehicle. The emergency stop control MRM refers to a control that automatically stops the vehicle when the driving of the vehicle is not handed over from the system control to the driver's operation. Note that, when the ADC unit 21 determines that it is necessary to activate the emergency stop control MRM, the emergency stop control MRM may be automatically activated without depending on the driver's operation. Also, for example, an emergency stop button or the like may be provided, and the emergency stop control MRM may be activated when an input from the driver is received.

[0043] The VDCCU 221 controls the stability of the vehicle behavior by executing a program stored in the ROM of the controller with the CPU. In order to stabilize the vehicle behavior, the VDC unit 22 is provided with various sensors such as a wheel speed sensor 222 that detects the rotation speed of the wheels, a yaw rate sensor (not shown) that detects the yaw rate of the vehicle, a steering angle sensor (not shown) that detects the steering angle of the steering wheels, and a lateral acceleration sensor that detects the lateral acceleration of the vehicle, and the detection values ​​detected by these sensors are transmitted to the VDCCU 221. The VDCCU 221 controls the brake pressure of each wheel by detecting the understeer tendency or oversteer tendency of the vehicle based on the detection values ​​of the various sensors, detecting the steering angle of the steering wheels and the lateral acceleration of the vehicle, and detecting skidding due to sudden braking or braking on an icy road surface.

[0044] The electric parking brake 223 controls the braking state of the wheels and the propeller shaft. Based on a command signal from the VDCCU 221, an electric actuator such as a motor is driven to activate and release the parking brake. In this embodiment, a case where an electric parking brake EPKB (Electric Parking Brake) is used as an example of the parking brake will be described, but the configuration of the parking brake is not limited thereto, and the braking state of the wheels and the propeller shaft may be controlled by the driver's operation of a lever, pedal, or the like.

[0045] The EBACU 231 assists in controlling the brake operation by executing a program stored in the ROM of the controller with the CPU. When the EBACU 231 reads the braking force required by the driver using a brake pedal sensor as the sensor 11, it controls a brake booster (not shown) and reduces the load of the pedal force applied by the driver using a motor.

[0046] Furthermore, the EBACU 231 controls the brake operation in an emergency. When an obstacle such as a vehicle or a stationary object that may interfere with the vehicle is detected based on output values ​​of various sensors such as a radar that detects obstacles around the vehicle as the sensor 11, a camera that captures images of the vehicle's surroundings, and a wheel speed sensor 232 that detects the rotation speed of the wheels, the EBACU 231 executes brake control in an emergency based on command values ​​from the ADC unit 21 and the VDC unit 22. Specifically, when it is determined that the brake operation is delayed or the braking control of the brake operation is insufficient despite the detection of an obstacle that may interfere with the vehicle, the EBACU 231 outputs a command signal to control the hydraulic friction brake or the electric parking brake 223 to ensure a necessary braking force.

[0047] In this embodiment, the EBA unit 23 is separately provided as a sub-system control unit, but the present invention is not limited to this. For example, the EBA unit 23 may be incorporated in the ADC unit 21, or may be omitted as necessary. In addition, the VDC unit 22 and the EBA unit 23 are each provided with various sensors separately, but for example, one wheel speed sensor may be shared by both the VDC unit 22 and the EBA unit 23.

[0048] The transmission 182 controls the shift state, such as upshifting or downshifting, based on the setting of the shift position. In this embodiment, a case where an AT (Automatic Transmission) that automatically performs stepwise shifting by gears is used will be described, but the present invention is not limited to this, and the shift state may be controlled using a CVT (Continuously Variable Transmission) that performs stepless shifting by continuously changing the gear ratio using a belt and a pulley. The shift position has a drive range and a non-drive range. The drive range includes a drive range that is set when the vehicle is traveling forward, and a reverse range that is set when the vehicle is traveling backward. The non-drive range includes a parking range that is set when the vehicle is stopped and fixes the transmission. There is also a neutral range that blocks the transmission of driving force from the drive mechanism to the wheels. The ADC unit 21 outputs a command value according to the state of the vehicle, and the transmission 182 sets the shift position and controls the shift state based on this command value.

[0049] As described above, in braking control under normal circumstances, when the VDC unit 22 receives a command value from the ADC unit 21, braking control is executed by the VDC unit 22 and the EBA unit 23 controlled by the VDC unit 22, the vehicle is decelerated by the hydraulic friction brake, and the braked state is maintained by operating the electric parking brake 223. However, if an abnormality occurs in the VDC unit 22, for example, if the input signal from the VDCCU 221 is interrupted and the VDC unit 22 cannot be controlled, or if the electric parking brake 223 has a malfunction and cannot be operated, the vehicle cannot be maintained in the braked state. For this reason, when the ADC unit 21 detects an abnormality in the VDC unit 22, it starts the emergency stop control MRM.

[0050] FIG. 5 shows a scene in which emergency stop control MRM is executed by the brake control device 20. When the ADC unit 21 detects an abnormal state of the VDC unit 22 at t1, it notifies the driver of the host vehicle V1 of the abnormal state of the VDC unit 22 at t2. The form of notifying the abnormal state is not particularly limited, but for example, a warning message such as "A system failure has occurred" and a content that prompts the driver to operate such as "Please operate manually" may be displayed on the presentation device 16 such as a display provided on the instrument panel of the host vehicle V1. Furthermore, a warning light may be turned on or an alarm sound may be emitted together with these displays to more strongly call attention. Note that the notification of the abnormal state to the driver is not a necessary configuration for the present invention and may be omitted as necessary. In this case, when the ADC unit 21 detects an abnormal state of the VDC unit 22 at t1, it autonomously executes the brake control from t3 to t5 without an instruction from the driver.

[0051] If no response is received from the driver for a predetermined time after notifying the driver of the abnormal state of the VDC unit 22, the ADC unit 21 starts the emergency stop control MRM. This makes it possible to execute braking control according to the urgency. The predetermined time is not particularly limited, but is at least the time until the driver who confirmed the notification of the abnormal state starts an operation, such as 4 seconds. In addition, if no response is received, this includes a case where the driver's reaction to the notification of the abnormal state, such as the driver's steering operation or muting of the alarm sound, cannot be confirmed. In such a case, the driver may be in a state where he or she cannot operate the vehicle V1, and an emergency stop is highly necessary.

[0052] When the ADC unit 21 starts the emergency stop control MRM, it activates the hydraulic friction brake at t3 and starts decelerating the host vehicle V1 while maintaining the autonomous driving control function. At this time, the ADC unit 21 may notify the content such as "emergency stop control is starting" on the presentation device 16 such as a display provided on the instrument panel of the host vehicle V1. By notifying the start of the emergency stop control MRM, the driver's anxiety due to the deceleration of the host vehicle V1 can be reduced. In addition, if a response such as steering operation by the driver is obtained at this time, the emergency stop control MRM may be switched from operation to the driver's operation. This allows more appropriate braking control to be executed at the time of emergency stop.

[0053] After decelerating the host vehicle V1 at t3, the ADC unit 21 determines the stopped state of the host vehicle V1 at t4. For example, using the output value of the wheel speed sensor 222 of the VDC unit 22 or the output value of the output rotary shaft sensor 181, when the output value of the wheel speed or the output rotary shaft is 0, it is determined that the vehicle speed is not detected, that is, the host vehicle is in a stopped state. When it is determined that the host vehicle V1 is in a stopped state, the ADC unit 21 controls the transmission 182 at t5 to set the shift range to the parking position. In this way, after the output value of the wheel speed or the output value of the output rotary shaft becomes 0, the shift range of the transmission 182 is set to the parking position without continuing to operate the hydraulic friction brake, thereby reducing the mechanical load and maintaining the stopped state of the host vehicle V1. The timing of releasing the operation of the hydraulic friction brake may be released at the same time as the shift range is set to the parking position, or may be released after the shift range is set to the parking position.

[0054] At t4, when the output value of the wheel speed cannot be detected, for example, when the input signal from VDCCU 221 is interrupted or when wheel speed sensor 222 is broken, only the output value of the output rotating shaft may be used. When the detection value of the output rotating shaft of the wheels is 0, this means that the vehicle speed is not detected. Therefore, even if the output value of the wheel speed cannot be detected, the stopped state of host vehicle V1 can be determined by using the output value of the output rotating shaft.

[0055] Furthermore, the output value of the wheel speed may be any one of the output value detected by the wheel speed sensor 222 of the VDC unit 22 and the output value detected by the wheel speed sensor 232 of the EBA unit 23. As a result, even if the output value of the wheel speed cannot be detected by the main system control unit, the stopped state of the host vehicle V1 can be determined using the output value of the wheel speed of the sub system control unit. Also, if the output value of the wheel speed cannot be detected by either the wheel speed sensor 222 of the VDC unit 22 or the wheel speed sensor 232 of the EBA unit 23, the output value of the output rotation shaft sensor 181 can be used. Even if a wide range of abnormalities occurs in the brake control device 20, the stopped state can be appropriately determined according to the state of the host vehicle V1.

[0056] If the shift range is set to the parking position even when the vehicle is not stopped, there is a risk of damage to components of the transmission 182. For this reason, it is preferable that the output value of the wheel speed and the output value of the output rotating shaft are all 0. More preferably, if the output value detected by the wheel speed sensor 222 of the VDC unit 22, the output value detected by the wheel speed sensor 232 of the EBA unit 23, and the output value detected by the output rotating shaft sensor 181 are all 0, the reliability of the determination of the stopped state is improved.

[0057] The estimated time from t3 to t4 may be used to determine the stopped state of the host vehicle V1 at t4. For example, the time required for the host vehicle V1 to stop is calculated from the vehicle speed of the host vehicle V1 at t1 and the deceleration caused by the hydraulic friction brake started at t3. The calculated time plus an error is taken as the estimated stop time t4, and the stopped state is determined when t4 is reached. If the output value of the wheel speed or the output value of the output rotating shaft is detected at the time of the estimated stop time t4 to determine the stopped state, it is not necessary to continue monitoring the output value from the sensor, and therefore the calculation load at the time of emergency stop can be reduced. In addition, the stopped state may be confirmed from the position information of the host vehicle V1 at the estimated stop time t4 using a GPS unit of the host vehicle position detection device 12 or the like. As a result, even if neither the output value of the wheel speed nor the output value of the output rotating shaft can be detected, the stopped state of the host vehicle V1 at the estimated stop time t4 can be determined, and the stopped state of the host vehicle V1 can be appropriately maintained according to the situation.

[0058] Braking control process Next, the braking control of this embodiment will be described with reference to Fig. 6. Fig. 6 is a flowchart showing an example of the braking control process executed by the braking control device 20 of this embodiment. The braking control process described below is executed at a predetermined time interval by the braking control device 20. In addition, it is assumed below that the autonomous driving control function of the control device 19 executes autonomous speed control and autonomous steering control, and performs lane keeping control to control the traveling position of the host vehicle in the width direction so that the host vehicle travels within the lane at a speed set by the driver.

[0059] First, when an abnormal state of VDC unit 22 is detected in step S1, ADC unit 21 outputs a notification to the occupant that an abnormal state of VDC unit 22 has been detected in step S2.

[0060] Next, in step S3, the ADC unit 21 judges whether or not to start the emergency stop control MRM. In response to the notification of the detection of the abnormal state of the VDC unit 22 output in step S2, for example, if the driver operates the steering wheel, the emergency stop control MRM is not started and the braking control process is terminated. In contrast, if no response is obtained for a predetermined time, such as when the driver does not operate the steering wheel, the process proceeds to step S4 and the emergency stop control MRM is started.

[0061] In step S5, the ADC unit 21 activates the hydraulic friction brakes to start decelerating the host vehicle V1. In the following step S6, the ADC unit 21 determines whether the host vehicle V1 is stopped or not based on the output value of the wheel speed sensor 222, the wheel speed sensor 232, or the output shaft sensor 181. If the output value of the wheel speed or the output shaft is 0, the ADC unit 21 determines that the host vehicle V1 is stopped, and proceeds to step S7. On the other hand, if the output value of the wheel speed or the output shaft is not 0, the ADC unit 21 repeats step S6 for a predetermined time.

[0062] If it is determined in step S6 that the host vehicle V1 is in a stopped state, the ADC unit 21 controls the transmission 182 to set the shift range to the parking position in step S7.

[0063] As described above, according to the driving control method and driving control device 1 of this embodiment, in the vehicle driving control method that executes braking control by autonomous driving control based on signals from the on-board braking control device 20 including the hydraulic friction brake and the electric parking brake 223, and the wheel speed output value or the output value of the output rotating shaft detected by the wheel speed sensor 222, the wheel speed sensor 232, and the output rotating shaft sensor 181, when an abnormal state of the braking control device 20 is detected, deceleration of the host vehicle V1 is started, and after the wheel speed output value or the output value of the output rotating shaft becomes 0, the shift range of the transmission 182 is set to the parking position without using the hydraulic friction brake. This reduces the mechanical load during an emergency stop and allows the host vehicle V1 to be kept stopped.

[0064] Furthermore, according to the cruise control method and cruise control device 1 of this embodiment, when the output value of the wheel speed cannot be detected, the shift range of the transmission 182 is set to the parking position based on the output value of the output rotating shaft. As a result, even if the output value of the wheel speed cannot be detected, the stopped state of the host vehicle V1 can be determined by using the output value of the output rotating shaft.

[0065] Furthermore, according to the driving control method and driving control device 1 of this embodiment, when both the output value of the wheel speed and the output value of the output rotating shaft are 0, the shift range of the transmission 182 is set to the parking position, so that the stopped state of the host vehicle V1 can be determined more preferably.

[0066] Furthermore, according to the cruise control method and cruise control device 1 of this embodiment, the braking control device 20 is controlled by a first braking control device (VDC unit) 22 and a second braking control device (EBA unit) 23 that backs up the first braking control device (VDC unit) 22, and the output value of the wheel speed is an output value detected by a wheel speed sensor 222 provided in the first braking control device (VDC unit) 22, or an output value detected by a wheel speed sensor 232 provided in the second braking control device (EBA unit) 23. As a result, even if the output value of the wheel speed cannot be detected by the main system control unit, the stopped state of the host vehicle V1 can be determined using the output value of the wheel speed of the sub system control unit.

[0067] Furthermore, according to the cruise control method and cruise control device 1 of this embodiment, when neither the output value detected by the wheel speed sensor 222 provided in the first braking control device (VDC unit) 22 nor the output value detected by the wheel speed sensor 232 provided in the second braking control device (EBA unit) 23 can be detected, the shift range of the transmission 182 is set to the parking position based on the output value of the output rotating shaft. As a result, even if a wide range of abnormalities occurs in the braking control device 20, the stopped state can be appropriately determined according to the state of the host vehicle V1.

[0068] Furthermore, according to the driving control method and driving control device 1 of this embodiment, when the output value detected by the wheel speed sensor 222 provided in the first braking control device (VDC unit) 22, the output value detected by the wheel speed sensor 232 provided in the second braking control (EBA unit) 23 unit, and the output value of the output rotating shaft are all 0, the shift range of the transmission 182 is set to the parking position, thereby improving the reliability of the determination of the stopped state.

[0069] Furthermore, according to the driving control method and driving control device 1 of this embodiment, when an abnormal state of the braking control device 20 is detected, a notification that an abnormal state has been detected is output to an occupant of the vehicle V1, and emergency stop control is initiated based on input from the occupant in response to the notification, so that braking control can be executed according to the urgency.

[0070] It should be noted that the above-described embodiment has been described to facilitate understanding of the present invention, and is not intended to limit the present invention. Therefore, the elements disclosed in the above embodiment are intended to include all design modifications and equivalents that fall within the technical scope of the present invention. [Explanation of symbols]

[0071] 1...Drive control device 11…Sensor 12...Vehicle position detection device 13…Map database 14…In-vehicle equipment 15. Navigation device 16...Presentation device 17...Input device 18a...Drive control device 18b...Steering control device 19...Control device 20...Brake control device

Claims

1. A vehicle driving control method for performing braking control by autonomous driving control based on a signal from an on-board braking control device including a hydraulic friction brake and an electric parking brake, and a wheel speed or an output value of an output rotating shaft detected by a sensor, comprising: When an abnormal state of the brake control device is detected, Start decelerating your vehicle, After the output value of the wheel speed or the output value of the output rotary shaft becomes 0, the shift range of the transmission is set to a parking position without using the hydraulic friction brake, A vehicle driving control method, comprising: setting a shift range of the transmission to a parking position based on an output value of the output rotating shaft when the output value of the wheel speed cannot be detected.

2. A vehicle driving control method for performing braking control by autonomous driving control based on a signal from an on-board braking control device including a hydraulic friction brake and an electric parking brake, and a wheel speed or an output value of an output rotating shaft detected by a sensor, comprising: When an abnormal state of the brake control device is detected, Start decelerating your vehicle, A vehicle driving control method in which, after both the output value of the wheel speed and the output value of the output rotating shaft become zero, the shift range of the transmission is set to a parking position without using the hydraulic friction brake.

3. The brake control device is controlled by a first brake control device and a second brake control device that backs up the first brake control device, the output value of the wheel speed is an output value detected by a wheel speed sensor included in the first braking control device, or an output value detected by a wheel speed sensor included in the second braking control device, 2. A vehicle driving control method as described in claim 1, wherein when neither the output value detected by the wheel speed sensor provided in the first braking control device nor the output value detected by the wheel speed sensor provided in the second braking control device can be detected, the shift range of the transmission is set to a parking position based on the output value of the output rotating shaft.

4. The brake control device is controlled by a first brake control device and a second brake control device that backs up the first brake control device, the output value of the wheel speed is an output value detected by a wheel speed sensor included in the first braking control device, or an output value detected by a wheel speed sensor included in the second braking control device, 3. The vehicle driving control method according to claim 2, wherein when the output value detected by the wheel speed sensor provided in the first braking control device, the output value detected by the wheel speed sensor provided in the second braking control device, and the output value of the output rotating shaft are all 0, the shift range of the transmission is set to a parking position.

5. When an abnormal state of the brake control device is detected, The vehicle driving control method according to any one of claims 1 to 4, further comprising outputting a notification to an occupant of the vehicle that an abnormal state has been detected, and initiating emergency stop control based on an input from the occupant in response to the notification.

6. A vehicle driving control device including a processor that executes braking control by autonomous driving control based on a signal from an on-board braking control device including a hydraulic friction brake and an electric parking brake, and a wheel speed or an output value of an output rotation shaft detected by a sensor, The processor, When an abnormal state of the brake control device is detected, Start decelerating your vehicle, After the output value of the wheel speed or the output value of the output rotary shaft becomes 0, the shift range of the transmission is set to a parking position without using a hydraulic friction brake, A vehicle travel control device that sets a shift range of the transmission to a parking position based on the output value of the output rotating shaft when the output value of the wheel speed cannot be detected.

7. A vehicle driving control device having a processor that performs braking control by autonomous driving control based on signals from an on-board braking control device including a hydraulic friction brake and an electric parking brake, and on wheel speeds or output values ​​of an output shaft detected by a sensor, The processor, When an abnormal state of the brake control device is detected, Start decelerating the vehicle, A vehicle driving control device that sets the shift range of the transmission to a parking position without using the hydraulic friction brake after both the output value of the wheel speed and the output value of the output rotating shaft become zero.

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