Ride Controls

Abstract

The present invention is a driving control device that allows lane changes based on driver steering intervention while continuing lane keeping control, comprising: an electronic control unit configured to set a target trajectory within a lane in which a vehicle is traveling, determine a target steering angle of the vehicle based on the target trajectory and a lateral position of the vehicle, apply a control torque to a steering shaft of the vehicle based on the target steering angle, reset the target trajectory in an adjacent lane in response to a change in the lateral position due to driver steering intervention that exceeds the control torque and the vehicle entering an adjacent lane, and determine the target steering angle by changing the target steering angle at the time of reset using a gradient function in response to the reset of the target trajectory.

Description

Technical Field

[0001] The present invention relates to a driving control device. Background Art

[0002] Japanese Patent Application Laid-Open No. 2017-149179 discloses a device for executing lane keeping control and automatic lane change control. The device interrupts lane keeping control when automatic lane change control is being executed during lane keeping control. Summary of the Invention

[0003] In the device described in Japanese Patent Application Laid-Open No. 2017-149179, lane keeping control is interrupted every time a lane change occurs. Therefore, the number of operations required to restart lane keeping control may increase. To suppress the increase in such operations, it is considered to implement lane changes based on manual intervention by the driver while the lane keeping control function is continued. In other words, it is considered to implement semi-automatic driving based on cooperation between the driver and the lane keeping control system during lane changes. However, when a lane change is implemented while the lane keeping control function is continued, the target steering angle of the lane keeping control system may change significantly at the moment the following lane is switched, causing discomfort to the driver. The technology provided by the present invention is capable of suppressing changes in the target steering angle when a lane change based on manual intervention by the driver is implemented while the lane keeping control function is continued.

[0004] A driving control device according to one embodiment of the present invention is a driving control device that allows lane changes due to a driver's steering intervention while continuing lane keeping control for controlling the vehicle to travel within a lane. The driving control device is characterized by comprising: an electronic control unit configured to: set a target trajectory within a lane along which the vehicle is traveling; obtain a lateral position of the vehicle; determine a target steering angle for the vehicle based on the set target trajectory and the obtained lateral position of the vehicle; apply a control torque to a steering axis of the vehicle based on the target steering angle determined by the electronic control unit; reset the target trajectory in an adjacent lane in response to the vehicle entering an adjacent lane due to a change in the lateral position of the vehicle due to the driver's steering intervention exceeding the control torque; and change the target steering angle at the time of reset of the target trajectory using a gradient function in response to the reset of the target trajectory in the adjacent lane, thereby determining the target steering angle after the vehicle enters the adjacent lane.

[0005] In this device, in response to the vehicle's lateral position changing due to the driver's steering intervention exceeding the control torque and the vehicle entering an adjacent lane adjacent to the lane, the target trajectory is reset in the adjacent lane. Then, in response to the target trajectory being reset in the adjacent lane, the target steering angle at the time of resetting the target trajectory is changed by using a gradient function to determine the target steering angle after the vehicle enters the adjacent lane. In this way, when the target trajectory is switched, the device is not able to determine the target steering angle based on the target trajectory and the lateral position of the vehicle, but is able to determine the target steering angle in the adjacent lane in a manner that gradually changes from the target steering angle at the time of resetting the target trajectory. As a result, when the device implements a lane change based on the driver's manual intervention while continuing lane maintenance control, it is possible to suppress the change in the target steering angle compared to the case where the target steering angle is determined based on the target trajectory and the lateral position of the vehicle.

[0006] In the above embodiment, in the gradient function, the gradient amount per unit time is larger than the prescribed value until a prescribed time has passed since the vehicle entered the adjacent lane, and becomes smaller than the prescribed value after the period has passed.

[0007] In the above embodiment, the electronic control unit is configured to apply the processing filter to the target steering angle when the target trajectory is set in the lane and the adjacent lane, and the electronic control unit is configured not to apply the processing filter to the target steering angle when the target trajectory is reset in the adjacent lane.

[0008] In the above aspect, the electronic control unit is configured to perform processing based on the target steering angle during the gradual change for resetting the target trajectory in the lane in response to the vehicle returning to the lane during the gradual change after entering the adjacent lane.

[0009] In the above-mentioned manner, the electronic control unit is configured to, when the driver ends the steering intervention before the vehicle enters the adjacent lane, determine the target steering angle as the target steering angle at the end of the driver's steering gradually approaches the target angle for following the lane before the gradual change as time passes from the end of the driver's steering.

[0010] This device prevents a sudden change in the target steering angle when the driver takes their hands off the steering wheel before the vehicle enters an adjacent lane. If the vehicle enters an adjacent lane after the driver takes their hands off the steering wheel while the target steering angle is steadily converging, the target steering angle in the adjacent lane is determined to gradually change from the target steering angle at the time of resetting the target trajectory. This device can thus suppress changes in the target steering angle even if the driver takes their hands off the steering wheel before the vehicle enters an adjacent lane.

[0011] In the above-mentioned manner, the electronic control unit is configured to generate a lane change trajectory from the lane to the adjacent lane, control the vehicle's travel in such a manner that the vehicle travels along the generated lane change trajectory, and reset the target trajectory in the adjacent lane in response to the vehicle's lateral position changing due to the driver's steering intervention during the lane change and the vehicle entering an adjacent lane adjacent to the lane.

[0012] With this configuration, when the driver's steering intervention causes the vehicle to enter an adjacent lane during a lane change using the automatic lane change function, the target steering angle is determined to gradually change from the target steering angle at the time of resetting the target trajectory. This device can thus suppress changes in the target steering angle even when the driver's steering intervention causes the vehicle to enter an adjacent lane during a lane change using the automatic lane change function.

[0013] According to one aspect of the present invention, when a lane change is performed by manual intervention of the driver while lane keeping control is continued, a change in the target steering angle can be suppressed. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Hereinafter, features, advantages, and technical and industrial significance of exemplary embodiments of the present invention will be described with reference to the accompanying drawings, wherein like symbols denote like elements.

[0015] Figure 1 This is a functional block diagram of an example of a vehicle including the travel control device according to the embodiment.

[0016] Figure 2A This is a diagram showing an example of a lane change scenario.

[0017] Figure 2B is a timing diagram of the state of the direction indicator.

[0018] Figure 2C It is the timing diagram of steering torque.

[0019] Figure 2D It is a timing diagram of lateral position deviation.

[0020] Figure 2E This is a timing diagram for setting the target trajectory.

[0021] Figure 2F It is a timing diagram for detecting discontinuities in the deviation between the target track and the lateral position of the vehicle.

[0022] Figure 2G It is a timing chart showing the gradual change period of the target steering angle.

[0023] Figure 2H is the timing diagram of the target steering angle.

[0024] Figure 3 This is a flowchart showing an example of the operation of the travel control device according to the embodiment.

[0025] Figure 4A This is a diagram showing an example of a lane change scenario.

[0026] Figure 4B is a timing diagram of the state of the direction indicator.

[0027] Figure 4C It is the timing diagram of steering torque.

[0028] Figure 4D It is a timing diagram of lateral position deviation.

[0029] Figure 4E This is a timing diagram for setting the target trajectory.

[0030] Figure 4F It is a timing diagram for detecting discontinuities in the deviation between the target track and the lateral position of the vehicle.

[0031] Figure 4G It is a timing chart showing the gradual change period of the target steering angle.

[0032] Figure 4H is the timing diagram of the target steering angle.

[0033] Figure 5 This is a flowchart showing an example of the operation of the travel control device according to the embodiment. DETAILED DESCRIPTION

[0034] Hereinafter, exemplary embodiments will be described with reference to the accompanying drawings. In the following description, the same or corresponding elements are denoted by the same reference numerals, and repeated description will not be repeated.

[0035] Structure of vehicle and driving control device

[0036] Figure 1 FIG. 1 is a functional block diagram of an example of a vehicle including the travel control device 1 according to the embodiment. Figure 1As shown, the driving control device 1 is mounted on a vehicle 2 such as a bus, a taxi, or a normal passenger car. The driving control device 1 controls the driving of the vehicle 2 so that the vehicle 2 drives within a lane. Specifically, the driving control device 1 controls the driving of the vehicle 2 by applying a control torque to the steering shaft of the vehicle 2 so that the vehicle 2 drives within the lane. Then, the driving control device 1 allows lane changes based on the driver's steering intervention while continuing the lane keeping control. For example, when the control torque is applied, the driver can perform a driving operation with an input torque greater than the control torque to move the vehicle to an adjacent lane adjacent to the lane in which the vehicle 2 is driving. In other words, the driving control device 1 can cooperate with the driver to drive the vehicle 2 under lane keeping control.

[0037] The vehicle 2 includes external sensors 3 , internal sensors 4 , an ECU (Electronic Control Unit) 5 , an HMI (Human Machine Interface) 6 , and actuators 7 .

[0038] External sensor 3 detects information about the external environment of vehicle 2. The external environment refers to the location and condition of objects surrounding vehicle 2. Detection results from external sensor 3 include the location, shape, and color of objects ahead of vehicle 2 in its lane. Objects include vehicles, pedestrians, traffic lights, and road markings. For example, external sensor 3 is a camera.

[0039] The camera is a device that captures images of the exterior of vehicle 2. For example, the camera is installed behind the windshield of vehicle 2. The camera acquires image information related to the exterior of vehicle 2. The camera can be a monocular camera or a stereo camera. A stereo camera has two imaging units configured to reproduce binocular parallax. The image information captured by the stereo camera also includes depth information.

[0040] External sensor 3 is not limited to a camera; it may also be a radar sensor or the like. A radar sensor uses radio waves (e.g., millimeter waves) or light to detect objects around vehicle 2. Examples of radar sensors include millimeter-wave radars and laser radars (LIDAR). Radar sensors transmit radio waves or light toward the periphery of vehicle 2 and detect objects by receiving the radio waves or light reflected by the objects.

[0041] Internal sensors 4 are detectors that detect the driving state of vehicle 2. Internal sensors 4 include a steering angle sensor. The steering angle sensor detects the amount of rotation of the steering shaft of vehicle 2. Internal sensors 4 may include a vehicle speed sensor, an acceleration sensor, and a yaw rate sensor. The vehicle speed sensor detects the speed of vehicle 2. As a vehicle speed sensor, for example, a wheel speed sensor provided for a wheel of vehicle 2 or a drive shaft rotating integrally with the wheel is used to detect the rotational speed of the wheel. An acceleration sensor detects the acceleration of vehicle 2. Acceleration sensors may also include a longitudinal acceleration sensor that detects the acceleration of vehicle 2 in the longitudinal direction and a lateral acceleration sensor that detects the acceleration of vehicle 2 in the left and right directions. A yaw rate sensor detects the yaw rate (rotational angular velocity) of the center of gravity of vehicle 2 about a vertical axis. For example, a gyroscope sensor may be used as the yaw rate sensor.

[0042] ECU5 controls the driving of vehicle 2. ECU5 is an electronic control unit having a CPU (Central Processing Unit), ROM (Read Only Memory), RAM (Random Access Memory), and a CAN (Controller Area Network) communication circuit. ECU5 is connected to a network that uses a CAN communication circuit, for example, and is communicatively connected to the components of vehicle 2. ECU5 operates the CAN communication circuit, inputs and outputs data, stores the data in RAM, loads programs stored in ROM into RAM, and executes the programs loaded into RAM, thereby achieving the functions described below. ECU5 can also be composed of multiple electronic control units.

[0043] The HMI 6 is an interface between the occupants (including the driver) of the vehicle 2 and the system implemented by the ECU 5. As an example, the HMI 6 includes a touch display capable of displaying information and accepting operation inputs from the occupants.

[0044] The actuator 7 is a device that controls the driving of the vehicle 2. It includes at least an engine actuator, a brake actuator, and a steering actuator. The engine actuator changes the amount of air supplied to the engine (for example, by changing the throttle opening) in response to driving operations or control signals from the ECU 5, thereby controlling the driving force of the vehicle 2. Furthermore, if the vehicle 2 is a hybrid vehicle or an electric vehicle, the engine actuator controls the driving force of the electric motor, which serves as the power source.

[0045] The brake actuator controls the braking system based on control signals from the ECU 5 and controls the braking force applied to the wheels of vehicle 2. A hydraulic brake system, for example, can be used as the braking system. Furthermore, if vehicle 2 includes a regenerative braking system, the brake actuator can control both the hydraulic and regenerative braking systems. The steering actuator controls the driving of the assist motor in the electric power steering system, which controls steering torque, based on control signals from the ECU 5. Thus, the steering actuator controls the steering torque of vehicle 2.

[0046] ECU functions

[0047] The driving control device 1 includes a track setting unit 10, a position acquisition unit 11, a steering angle determination unit 12, a lane keeping control unit 13, a trajectory generation unit 14, and a lane change control unit 15 as functional components. If the vehicle 2 does not have an automatic lane change function, the driving control device 1 may not include the lane change control unit 15. Figures 2A to 2H , the functions of the travel control device 1 are described. Figure 2A This is a diagram showing an example of a lane change scenario.

[0048] exist Figure 2A In the example, vehicle 2 is traveling on a single-sided two-lane road. Figure 2A As shown, vehicle 2 is traveling in the first lane L1 while the lane keeping function is engaged. At time t1, the driver of vehicle 2 turns on the turn signal indicator to change lanes to the second lane L2 adjacent to the first lane L1. The driver then operates the steering wheel from time t2, using an input torque exceeding the control torque to change the lateral position of vehicle 2 so that vehicle 2 approaches the second lane L2. At time t3, vehicle 2 crosses the boundary line VL between the first lane L1 and the second lane L2, entering the second lane L2. The driver then removes their hands from the steering wheel at time t4 and thereafter turns off the turn signal indicator. At this point, vehicle 2 is located in the center of the second lane L2, traveling within the second lane L2 while the lane keeping function is engaged.

[0049] Figure 2B and Figure 2C This is a timing chart related to the above-mentioned actions of the driver. Figure 2B is a timing diagram of the state of the direction indicator, Figure 2C is a timing diagram of the steering torque. The steering torque is detected by, for example, a torque sensor provided on the steering shaft of the vehicle 2. A left turn of the steering wheel represents a positive value, and a right turn of the steering wheel represents a negative value. Figure 2B and Figure 2CAs shown in FIG, the direction indicator is turned on at time t1 before time t2 when the driver grasps the steering wheel and starts turning, and is turned off after time t4 when the driver takes his hands off the steering wheel. Figure 2C As shown, the steering torque is detected while the driver applies force to the steering wheel.

[0050] The trajectory setting unit 10 sets a target trajectory within the lane in which the vehicle 2 is traveling. The target trajectory is the trajectory targeted by the lane keeping control unit 13 and is, for example, set to pass through the center of the lane in which the vehicle 2 is traveling. The trajectory setting unit 10 obtains the position of the lane boundary line detected by the external sensor 3 and sets the target trajectory. For example, if the vehicle 2 is traveling in the first lane L1, the trajectory setting unit 10 sets the first trajectory TL1 at the center of the first lane L1.

[0051] The position acquisition unit 11 acquires the lateral position of the vehicle 2. The position acquisition unit 11 acquires the position of the lane boundary line detected by the external sensor 3, and acquires the lateral position of the vehicle 2 in the lane in which the vehicle 2 is traveling.

[0052] The steering angle determination unit 12 determines a target steering angle θtgt for vehicle 2 based on the target trajectory set by the trajectory setting unit 10 and the lateral position of vehicle 2 obtained by the position acquisition unit 11. The target steering angle θtgt is a control parameter used by the lane keeping control unit 13 to drive the assist motor. For example, if there is a deviation between the first trajectory TL1 set by the trajectory setting unit 10 and the lateral position of vehicle 2, the steering angle determination unit 12 sets the target steering angle θtgt as a steering angle that eliminates the deviation.

[0053] The lane keeping control unit 13 applies a control torque to the steering axis of vehicle 2 based on the target steering angle θtgt determined by the steering angle determination unit 12. The magnitude of the control torque can be set to increase in accordance with the target steering angle θtgt, or it can be set to a constant value. By setting the target steering angle to eliminate the deviation between the target trajectory and the lateral position of vehicle 2 and applying the control torque to achieve the target steering angle, for example, vehicle 2 traveling in the first lane L1 follows the first trajectory TL1, thereby automatically traveling within the first lane L1. In this way, the lane keeping function is achieved through the collaboration of the trajectory setting unit 10, the position acquisition unit 11, the steering angle determination unit 12, and the lane keeping control unit 13.

[0054] Figures 2D to 2H This is a timing chart related to the operations of the trajectory setting unit 10 , the position acquisition unit 1 , the steering angle determination unit 12 , and the lane keeping control unit 13 . Figure 2D is the timing diagram of the lateral position deviation, Figure 2E This is a timing diagram related to the setting of the target track. Figure 2Fis a timing diagram for detecting discontinuities in the deviation between the target track and the lateral position of the vehicle, Figure 2G is a timing diagram showing the gradual change period of the target steering angle, Figure 2H is the timing diagram of the target steering angle.

[0055] Figure 2D This is a time series diagram of the deviation between the target track and the lateral position of vehicle 2. The deviation to the left (upward in the figure) of the target track as viewed from vehicle 2 is negative, and the deviation to the right (downward in the figure) of the target track as viewed from vehicle 2 is positive. When the driver starts turning at time t2, vehicle 2 leaves the first track TL1, which is the target track, and moves toward the second lane L2. Therefore, as Figure 2D As shown, the absolute value of the deviation between the first track TL1 and the lateral position of the vehicle 2 gradually increases from time t2 (the deviation between the first track TL1 and the lateral position of the vehicle 2 increases in the negative direction).

[0056] Figure 2H The target steering angle θtgt is a time chart determined by the steering angle determination unit 12. The target steering angle θtgt is a positive value when the steering wheel is turned left, and a negative value when the steering wheel is turned right. From time t2 onwards, the deviation between the first track TL1 and the lateral position of the vehicle 2 gradually increases in the negative direction, and then, as shown in FIG. Figure 2H As shown, from time t2, the target steering angle θtgt is set to a negative steering angle that rotates in the opposite direction to the driver's steering. As a result, the lane keeping control unit 13 applies a control torque to the steering shaft in such a way that the steering angle of the vehicle 2 becomes the target steering angle θtgt. In other words, a control torque is applied to the steering wheel in the opposite direction to the driver's steering wheel operation, and the driver applies an input exceeding the control torque to the steering wheel, whereby the vehicle 2 gradually moves closer to the second lane L2. In this way, the driver operates the vehicle 2 while feeling the load on the steering wheel, as shown in FIG. Figure 2C As shown, the steering torque is detected as a left turn (positive direction) from time t2. Furthermore, the target steering angle from time t2 to time t3 is calculated by multiplying the target steering angle obtained based on the deviation between the first track TL1 and the lateral position of vehicle 2 by a predetermined coefficient (e.g., 0.1 to 0.9). This ensures that the target steering angle is conservatively set relative to the driver's steering direction. When the driver releases their hands, the target steering angle smoothly changes to a value close to the target steering angle at the moment the driver releases their hands from the steering wheel, thereby stabilizing the movement of vehicle 2.

[0057] By the driver's operation, at time t3, the vehicle 2 enters the second lane L2 from the first lane L1. At this time, since the lane in which the vehicle 2 is traveling has changed, the track setting unit 10 resets the second track TL2 as the target track at the center of the second lane L2. Figure 2E As shown, at the moment vehicle 2 moves from first lane L1 to second lane L2 (time t3), the target trajectory is reset from first trajectory TL1 to second trajectory TL2. The trajectory setting unit 10, for example, identifies the moment vehicle 2 moves from first lane L1 to second lane L2 based on the detection results of external sensor 3 and resets the target trajectory to second trajectory TL2 at that moment. In this way, the trajectory setting unit 10 resets the target trajectory in the adjacent lane in response to a change in the lateral position of vehicle 2 due to driver-induced steering intervention exceeding the control torque, resulting in the vehicle 2 entering an adjacent lane adjacent to the lane in which vehicle 2 is traveling.

[0058] At the moment when the vehicle 2 enters the second lane L2 from the first lane L1 (time t3), the target track is switched from the first track TL1 to the second track TL2. Figure 2D As shown, the deviation between the target trajectory and the lateral position of the vehicle 2 changes rapidly. The steering angle determination unit 12 plots the deviation between the target trajectory and the lateral position of the vehicle 2 and determines that the change is discontinuous if the absolute value of the deviation change is greater than a predetermined value. Figure 2F This is a timing diagram that detects changes in lateral position deviation above a threshold as discontinuous changes. Figure 2F As shown, at the time (time t3) when the vehicle 2 enters the second lane L2 from the first lane L1, a discontinuous change in the deviation between the target track and the lateral position of the vehicle 2 is detected.

[0059] As described above, the steering angle determination unit 12 eliminates Figure 2D Therefore, at time t3, when the sign of the deviation between the target track and the lateral position of the vehicle 2 is reversed, Figure 2H As shown, at time t3, the target steering angle θlat is set as the target steering angle. Figure 2H The target steering angle is shown by the dotted line in the middle. In this case, since the control torque is applied in the reverse direction, Figure 2C As shown by the middle dashed line, the positive and negative signs of the steering torque are also suddenly reversed, which has a great influence on the driver's steering.

[0060] Therefore, the steering angle determination unit 12 detects Figure 2FIn the case of a discontinuous change in the deviation between the target trajectory shown and the lateral position of the vehicle 2, the target steering angle θhold at that moment is stored. That is, the steering angle determination unit 12 stores the target steering angle θhold when the target trajectory is reset. Then, the steering angle determination unit 12 uses a gradient function to change the stored target steering angle θhold, thereby determining the target steering angle θtgt after the vehicle 2 enters the second lane L2. The gradient function is a function that suppresses sudden changes and gradually changes the value, and is an exponential function as an example. Alternatively, the gradient function can also be a rate limiter that acts based on the difference with the previous value. In addition, the rate limiter can also act in a manner that increases the gradient amount at the beginning of the gradient and decreases the gradient amount after a specified time. The following illustrates the case of using an exponential function as a gradient function. According to the following formula (1), the steering angle determination unit 12 determines the target steering angle θtgt after time t3.

[0061] θtgt=θlat+(θhold-θlat)·e -at (1)

[0062] Therefore, if Figure 2H As shown in , the target steering angle θtgt changes smoothly. Then, as Figure 2C As shown, the sudden change of the steering torque is suppressed. In the case of using an exponential function, the change in the target steering angle θtgt is large just after the lane switch, and thereafter, the change in the target steering angle θtgt is blunted. That is, in the period from the moment vehicle 2 enters the adjacent lane to the time elapsed for a prescribed time (the period just after the lane switch), the gradient per unit time is larger than the prescribed value, and after the period just after the lane switch, the gradient per unit time is smaller than the prescribed value. The prescribed value is a pre-set steering angle. By increasing the change in the target steering angle θtgt just after the lane switch, it is possible to limit the return to the original lane, and it is also possible to convey the lane switch as information to the driver. Thereafter, by smoothly gradient-changing the target steering angle θtgt, the vehicle behavior becomes smooth. In addition, Figure 2G The gradual change period ends, for example, when the difference between the target steering angle θtgt and the target angle (target value) for following the lane before the gradual change becomes equal to or smaller than a predetermined value.

[0063] The trajectory generation unit 14 generates a lane change trajectory for the vehicle 2 from the lane in which it is traveling to the adjacent lane. The trajectory generation unit 14 generates the lane change trajectory based on the detection results of the external sensor 3. The lane change control unit 15 controls the travel of the vehicle 2 so that the vehicle 2 travels along the lane change trajectory generated by the trajectory generation unit 14. The trajectory generation unit 14 and the lane change control unit 15 are components that realize the automatic lane change function. When the lateral position of the vehicle 2 is changed by the steering intervention of the driver, the lane change control unit 15 controls the steering axis of the vehicle 2 in a manner that reduces the deviation between the lateral position of the vehicle 2 and the lane change trajectory. In other words, the lane change control unit 15 can cooperate with the driver to cause the vehicle 2 to travel under lane change control.

[0064] In the lane change control, when the vehicle 2 enters the adjacent lane from the lane it is traveling in while the driver is steering, Figures 2A to 2H That is, the gradual change process of the target steering angle θtgt is executed regardless of whether the lane change control is in effect or not.

[0065] Operation of the driving control system

[0066] Figure 3 This is a flowchart showing an example of the operation of the travel control device according to the embodiment. Figure 3 In the flowchart shown, the driving control device 1 is executed when, for example, a start button of the lane keeping function provided in the vehicle 2 is turned on.

[0067] like Figure 3 As shown, as step S10, the driving control device 1 obtains the driver's intention to change lanes automatically. For example, the driving control device 1 receives an ON operation of the direction indicator or an approval operation from the HMI 6 in response to an automatic lane change proposal made via the HMI 6 or the like.

[0068] Next, in step S12, the driving control device 1 determines whether to execute an automatic lane change. For example, if the driver has turned on the turn signal indicator or approved the automatic lane change proposal through the HMI 6, the driving control device 1 determines to execute the automatic lane change (step S12: Yes) and executes the automatic lane change (step S14). If the driver has not approved the automatic lane change proposal, the driving control device 1 does not execute the automatic lane change (step S12: No).

[0069] Next, in step S16, the driving control device 1 obtains the driver's lane change intention based on the steering. The driving control device 1 obtains the driver's steering state. If the driver is turning toward an adjacent lane, the driving control device 1 determines that the driver has a lane change intention based on the steering (step S18: Yes). If the driver is not turning toward an adjacent lane, the driving control device 1 determines that the driver has no lane change intention based on the steering (step S18: No).

[0070] If it is determined that there is a lane change intention based on the driver's steering (step S18: Yes), the driving control device 1 performs a switching process as step S20. In the driving control device 1, the target track is switched when the time comes to cross the lane, and the target track is not switched when the time comes to not cross the lane (see Figure 2E ). Next, as step S22, the travel control device 1 detects the deviation between the target track and the lateral position of the vehicle 2 (refer to Figure 2D ).

[0071] Next, as step S24, the driving control device 1 determines whether a lane switch is detected. If the deviation between the target track obtained by the driving control device 1 in step S22 and the lateral position of the vehicle 2 is not greater than a prescribed value, the driving control device 1 determines that a lane switch is not detected (step S24: No). If the deviation between the target track obtained by the driving control device 1 in step S22 and the lateral position of the vehicle 2 is greater than a prescribed value, the driving control device 1 determines that a lane switch is detected (step S24: Yes, refer to Figure 2F ).

[0072] If it is determined that a lane change is detected (step S24: Yes), the travel control device 1 performs a gradual change process of the target steering angle as step S26. The travel control device 1 uses the above formula (1) to gradually change the target steering angle (see Figure 2H ) is determined by means of

[0073] When step S26 is completed, the travel control device 1 performs steering angle control based on the gradually changing target steering angle θtgt in step S28. This can avoid the uncomfortable feeling caused by the change in steering torque when crossing lanes.

[0074] If it is determined that the driver does not intend to change lanes due to steering (step S18: NO), the driving control device 1 implements steering angle control based on the unmodified target steering angle θtgt in step S28. Specifically, if automatic lane change is executed (step S14), the system continues to execute automatic lane change based on the unmodified target steering angle θtgt. If automatic lane change is not executed, lane keeping control is executed based on the unmodified target steering angle θtgt.

[0075] If the driving control device 1 determines that a lane change has not been detected (step S24: No), the driving control device 1 then performs steering angle control based on the ungradually changing target steering angle θtgt in step S28. Specifically, although the driver is steering, the vehicle 2 has not crossed the boundary line VL between the first lane L1 and the second lane L2, and therefore lane keeping control is being performed based on the ungradually changing target steering angle θtgt.

[0076] When the steering angle control ends, Figure 3 The flowchart shown ends. When the flowchart ends, the process is executed again from step S10 until the end condition is satisfied. The end condition is, for example, when the end button of the lane keeping control is set to ON. Figure 3 The flowchart shown can suppress target steering angle changes that occur when crossing lanes when the steering angle is manually adjusted before crossing lanes during automatic lane change, or when the lane change is performed by manually adjusting the steering angle without selecting automatic lane change.

[0077] Other actions of the travel control device

[0078] Next, the operation of the driving control device 1 in a driving scenario in which the driver takes his hands off the steering wheel during a lane change based on the driver's steering, and the vehicle 2 subsequently crosses lanes due to the automatic lane change function or inertia will be described.

[0079] Figure 4A is a diagram showing an example of a lane change scenario, and Figure 2A same. Figure 4B is a timing diagram of the state of the direction indicator, Figure 4C is the timing diagram of steering torque. Figures 2A to 2C The difference is that at time t21 before vehicle 2 crosses the lane, the driver takes his hands off the steering wheel. Figure 4C As shown, the steering torque becomes substantially zero at time t21.

[0080] Figure 4D is the timing diagram of the lateral position deviation, Figure 4E This is a timing diagram related to the setting of the target track. Figure 4F is a timing diagram for detecting discontinuities in the deviation between the target track and the lateral position of the vehicle. Figure 4G is a timing diagram showing the gradual change period of the target steering angle, Figure 4H is a timing diagram of the target steering angle. As described above, in the case of cooperative driving with the driver, the size of the target steering angle is conservatively set assuming that the driver takes his hands off the steering wheel. For example, Figure 4H As shown, from the moment the steering wheel is gripped (time t2) to the moment the steering wheel is released (time t21), the target steering angle determined based on the deviation between the target track and the lateral position of the vehicle 2 is multiplied by a predetermined coefficient, and the target steering angle θtgt is set to be small. Then, the steering angle determination unit 12 sets the target steering angle at time t21, which is the time when the driver's steering operation ends, to gradually approach the target angle for following the lane before the gradual change as time passes from the end of the driver's steering operation. Thus, as Figure 4H As shown, it is possible to avoid the target steering angle from switching to the target steering angle θdrv determined based on the deviation between the target track and the lateral position of the vehicle 2 at time t21. Then, the target steering angle θtgt converges smoothly from time t21. Figures 4D to 4F As shown, Figures 2D to 2F Likewise, at time t3 , the vehicle 2 enters the second lane L2 from the first lane L1 , and the target track is switched from the first track TL1 to the second track TL2 .

[0081] Here, when the target steering angle θtgt is determined based on the deviation between the target trajectory at time t3 and the lateral position of the vehicle 2, Figure 2H Similarly, the target steering angle is θlat. θhold is set to a small value from the moment the driver releases their hands on the steering wheel. Therefore, applying θlat directly to equation (1) may result in a large overshoot, preventing smooth vehicle motion. Therefore, θlat can be corrected to a smaller value, θtgt1, by multiplying it by a correction coefficient C (e.g., 0.1 to 0.5). Alternatively, assuming a as the gradual change rate and b as the target steering ratio, θtgt1 can be calculated using equation (2) below.

[0082] θtgt1=θlat×C×(1-(1-a)·(1-b)) (2)

[0083] Using the above-mentioned θtgt1, the target steering angle during the gradual change period is expressed by the following mathematical formula (3).

[0084] θtgt=θtgt1+(θhold-θtgt1)·e -at (3)

[0085] Therefore, if Figure 4H As shown, the target steering angle θtgt changes smoothly. Furthermore, the gradual change rate is used when gradually changing the steering angle toward the target steering angle during driver operation. The gradual change rate indicates the current progress of the gradual change (0 for the start of the gradual change and 1 for the completion of the gradual change). The target steering ratio is the target angle gain during driver operation divided by the target angle gain during normal operation (when overshoot is not suppressed). This value represents the ratio of the gain during driver operation to the gain during normal operation.

[0086] Figure 5 The operation of the travel control device 1 is shown in the timing chart shown in FIG4 . Figure 5 This is a flowchart showing an example of the operation of the travel control device 1 according to the embodiment. Figure 5 The flowchart shown is executed by the travel control device 1 when, for example, a start button of the lane keeping function provided in the vehicle 2 is turned on.

[0087] like Figure 5 As shown, the driving control device 1 performs lane change processing as step S100. Figure 3 Steps S10 to S14 are the same.

[0088] Next, as step S102, the driving control device 1 performs a gradual change process of the target steering angle. Figure 3 The processing of steps S16 and S26 is the same.

[0089] Next, in step S104, the driving control device 1 determines whether the driver has taken his hands off the steering wheel before the lane change. The driving control device 1 determines whether the driver has taken his hands off the steering wheel before the lane change based on, for example, the magnitude of the steering torque.

[0090] If it is determined that the driver has taken his hands off the steering wheel before the lane change (step S104: Yes), the driving control device 1 changes the target steering angle after the hands-off to a target angle that smoothly converges to the lane before the gradual change. Figure 3 The processing of steps S20 to S28 is the same as that of Figure 5 When the flowchart shown ends, the process is executed again from step S100 until the end condition is satisfied. The end condition is, for example, when the end button of the lane keeping control is turned on. Figure 5 The flowchart shown can suppress the target steering angle change that occurs when crossing lanes when the steering angle is manually adjusted before crossing lanes during automatic lane change and the driver lets go of the steering wheel, or when the lane change is performed without selecting automatic lane change and the steering angle is manually adjusted and the driver lets go of the steering wheel.

[0091] Summary of implementation methods

[0092] In response to the lateral position of vehicle 2 changing due to driver-induced steering intervention exceeding the control torque, and vehicle 2 entering a second lane L2 adjacent to first lane L1, the driving control device 1 resets the target trajectory in second lane L2. Then, in response to the reset of the target trajectory in second lane L2, the target steering angle θtgt at the time of target trajectory reset is varied using a gradual function, thereby determining the target steering angle θtgt after vehicle 2 enters second lane L2. In this way, when the target trajectory is switched, the driving control device 1 can determine the target steering angle θtgt for second lane L2 by gradually varying from the target steering angle θtgt at the time of target trajectory reset, rather than determining the target steering angle based on the target trajectory and the lateral position of vehicle 2. Consequently, when the driving control device 1 performs a lane change based on driver manual intervention while maintaining lane keeping control, it can suppress changes in the target steering angle compared to a case where the target steering angle is determined based on the target trajectory and the lateral position of vehicle 2.

[0093] The driving control device 1 can prevent a sudden change in the target steering angle when the driver takes their hands off the steering wheel before the vehicle 2 enters the second lane L2. Then, if the vehicle 2 enters the second lane L2 while the target steering angle smoothly converges after the hands-off release, the target steering angle in the adjacent lane is determined to gradually change from the target steering angle θhold at the time of resetting the target trajectory. Thus, the driving control device 1 can suppress changes in the target steering angle even if the driver takes their hands off the steering wheel before the vehicle 2 enters the second lane L2.

[0094] In the driving control device 1, if the vehicle 2 enters an adjacent lane due to driver steering intervention during a lane change using the automatic lane change function, the target steering angle for the second lane L2 is determined to gradually change from the target steering angle at the time of resetting the target trajectory. This allows the driving control device 1 to suppress changes in the target steering angle even if the vehicle 2 enters the second lane L2 due to driver steering intervention during a lane change using the automatic lane change function.

[0095] Modifications

[0096] Various exemplary embodiments have been described above, but the present invention is not limited to the exemplary embodiments described above, and various omissions, substitutions, and changes are possible.

[0097] In the above embodiment, as shown in mathematical formula (1), the difference between the target steering angle θhold before the discontinuity and the target steering angle θlat after the discontinuity affects the target steering angle θtgt. When a processing filter such as a low-pass filter is applied to the target steering angle, the difference may not be calculated correctly. In addition, sometimes the responsiveness is reduced due to the application of the low-pass filter. Therefore, when mathematical formula (1) is applied, the target steering angle is determined by releasing the low-pass filter applied to the target steering angle, and a smooth target steering angle θtgt can be obtained. This filter unlocking is temporarily performed corresponding to the reset of the target track in the adjacent lane.

Claims

1. A driving control device that allows lane changes due to a driver's steering intervention while continuing lane keeping control for controlling the vehicle to stay within a lane, the driving control device comprising: An electronic control unit configured to: setting a target trajectory within the lane along which the vehicle is traveling, Obtain the lateral position of the vehicle, Determine the target steering angle of the vehicle based on the set target trajectory and the obtained lateral position of the vehicle, applying a control torque to the steering shaft of the vehicle according to the target steering angle determined by the electronic control unit, In response to the lateral position of the vehicle changing due to the steering intervention by the driver exceeding the control torque and the vehicle entering an adjacent lane adjacent to the lane, resetting the target trajectory in the adjacent lane, Corresponding to the resetting of the target trajectory in the adjacent lane, the target steering angle at the time of resetting the target trajectory is changed by using a gradient function to determine the target steering angle after the vehicle enters the adjacent lane, The electronic control unit is configured to apply a processing filter to the target steering angle when the target trajectory is set in the lane and an adjacent lane. The electronic control unit is configured not to apply the processing filter to the target steering angle if the target trajectory is reset in the adjacent lane.

2. The travel control device according to claim 1, wherein: In the gradient function, a gradient amount per unit time is larger than a predetermined value during a period from when the vehicle enters the adjacent lane to when a predetermined time has passed, and after the period has passed, the gradient amount per unit time is smaller than the predetermined value.

3. The travel control device according to claim 1 or 2, wherein: The electronic control unit is configured to perform processing according to the target steering angle in the gradual transition for resetting the target trajectory in the lane in response to the vehicle returning to the lane in the gradual transition after the vehicle enters the adjacent lane.

4. The travel control device according to claim 1 or 2, wherein: The electronic control unit is configured to, when the driver ends the steering intervention before the vehicle enters the adjacent lane, determine the target steering angle so that the target steering angle at the time the driver's steering ends gradually approaches the target angle for following the lane before the gradual change as time passes from the end of the driver's steering.

5. The travel control device according to claim 1 or 2, characterized in that: The electronic control unit is configured to generate a lane change trajectory from the lane to the adjacent lane, The electronic control unit is configured to control the driving of the vehicle in such a manner that the vehicle drives along the generated lane change trajectory. The electronic control unit is configured to reset the target trajectory in the adjacent lane in response to a change in the lateral position of the vehicle due to a steering intervention by the driver in a lane change and the vehicle entering an adjacent lane adjacent to the lane.

Images