Lane change assistance device

Abstract

A lane change assistance device is configured to estimate a vehicle speed of another vehicle traveling on a lane of a lane change destination, determine a minimum length of a space on the lane of the lane change destination required for lane change on the basis of the vehicle speed of the other vehicle, estimate an actual length of the space on the lane of the lane change destination, and assist the lane change. The present invention determines whether or not a lane change is possible on the basis of a minimum length and an actual length, and when the determination is not possible, calculates a target relative speed of the own vehicle with respect to the other vehicle on the basis of an allowable acceleration / deceleration of the own vehicle, and controls the vehicle speed of the own vehicle so that the relative speed becomes the target relative speed. The present invention searches for a space on a lane of a lane change destination required for lane change.

Description

Technical Field

[0001] The invention relates to a lane change assist device for vehicles such as automobiles. Background Art

[0002] As one of the lane change assist devices, there is known a lane change assist device that determines whether a lane change of the own vehicle is possible, and when the lane change of the own vehicle is not possible, controls the speed of the own vehicle to explore whether there is no space for lane change in the lane of the lane change destination.

[0003] For example, Japanese Patent Application Laid-Open No. 2021-149119 discloses a lane change assist device that determines whether a lane change of a vehicle is approved. If the lane change is not approved, the vehicle is accelerated or decelerated (accelerated or decelerated) according to the speed of other vehicles traveling in the lane of the lane change destination to determine whether the lane change of the vehicle can be performed. According to this lane change assist device, it is possible to more effectively determine whether a lane change can be performed than when the vehicle is not accelerated or decelerated. Summary of the invention

[0004] However, in conventional lane change assist devices such as the device described in Japanese Patent Application Laid-Open No. 2021-149119, the urgency of the lane change is not taken into consideration, and the vehicle is accelerated or decelerated based on the speed of other vehicles traveling in the lane of the lane change destination. Therefore, it is impossible to appropriately explore the space for lane change while controlling the speed of the vehicle based on the driving conditions of the vehicle such as the urgency of the lane change.

[0005] The present invention provides a lane change assist device which is improved so as to be able to appropriately explore a space for lane change by controlling the speed of the own vehicle according to the driving condition of the own vehicle such as the urgency of the lane change.

[0006] According to the present invention, there is provided a lane change assist device (100), comprising:

[0007] An object (target object) information acquisition device (18) acquires information on object targets around the own vehicle (102); and

[0008] The control unit (driving assistance ECU 10) is configured as follows:

[0009] estimating the vehicle speed (Vad) of other vehicles (112, 114) traveling in the lane (110) of the lane change destination (lane change target) based on the information obtained by the object mark information obtaining device;

[0010] Determining a minimum length (Lsre) of a space on a lane of a lane change destination required for the own vehicle to change lanes based on the estimated speed of the other vehicle (S10);

[0011] Estimate the actual length (Ls) of the space on the lane at the lane change destination based on the information acquired by the object marker information acquisition device;

[0012] Whether or not the lane change of the own vehicle to the lane change destination is possible is determined based on the minimum length and the actual length ( S20 ).

[0013] The control unit (driving assistance ECU 10) is configured to, when it is determined that it is not possible (S20), set the allowable acceleration and deceleration (Gxma) of the own vehicle based on the driving condition of the own vehicle (S30), calculate the target relative speed (Vrma) of the own vehicle with respect to other vehicles based on the allowable acceleration and deceleration (S40), control the speed of the own vehicle in such a way that the relative speed of the own vehicle with respect to other vehicles becomes the target relative speed, and explore the space on the lane of the lane change destination required for the own vehicle to change lanes (S80, S100, S130, S150).

[0014] According to the above configuration, when the determination is not possible, the permissible acceleration / deceleration of the own vehicle is set based on the driving condition of the own vehicle, and the target relative speed of the own vehicle with respect to other vehicles is calculated based on the permissible acceleration / deceleration. Furthermore, while controlling the speed of the own vehicle so that the relative speed of the own vehicle with respect to other vehicles becomes the target relative speed, the space on the lane of the lane change destination required for the own vehicle to change lanes is searched (searched).

[0015] Thus, the speed of the own vehicle can be controlled so that the relative speed of the own vehicle to other vehicles traveling in the lane of the lane change destination becomes the target relative speed calculated according to the driving condition of the own vehicle. Therefore, compared with the case where the own vehicle is accelerated or decelerated only according to the speed of other vehicles to explore the space, the space on the lane of the lane change destination required for the own vehicle to change lanes can be appropriately explored.

[0016] In one embodiment of the present invention, the control unit (driving assistance ECU 10) is configured to control the speed of the own vehicle so that the relative speed of the own vehicle to the other vehicles becomes the target relative speed, while exploring a space longer than the minimum length on the lane of the lane change destination (S80), when the speed of the own vehicle (Vo) is greater than the speed of other vehicles (Vad) (S50) and the speed of the own vehicle is less than the sum of the speed of other vehicles and the target relative speed (Vad+Vrma) (S60).

[0017] In another embodiment of the present invention, the control unit (driving assistance ECU 10) is configured to determine an achievable relative speed (Vrmaa) of the own vehicle with respect to other vehicles when the speed of the own vehicle is greater than the speed of other vehicles (S50) and the speed of the own vehicle is greater than the sum of the speed of other vehicles and the target relative speed (Vad+Vrma) (S60), and determine a corrected minimum length (Lsrea) of a space in which the own vehicle can change lanes based on the achievable relative speed (S90); while controlling the speed of the own vehicle so that the relative speed of the own vehicle with respect to other vehicles becomes an achievable relative speed (-Vrmaa), the control unit explores a space greater than the corrected minimum length on the lane at the lane change destination (S100).

[0018] Furthermore, in another embodiment of the present invention, the control unit (driving assistance ECU 10) is configured to control the speed of the own vehicle so that the relative speed of the own vehicle to the other vehicles becomes the target relative speed, while exploring a space longer than the minimum length on the lane of the lane change destination (S130), when the speed of the own vehicle is lower than the speed of other vehicles (S50) and the speed of the own vehicle is higher than the difference (Vad-Vrma) between the speed of other vehicles and the target relative speed (S110).

[0019] Furthermore, in another embodiment of the present invention, the control unit (driving assistance ECU 10) is configured to determine an achievable relative speed (Vrmaa) of the own vehicle with respect to other vehicles, and determine a corrected minimum length (Lsrea) of a space in which the own vehicle can change lanes based on the achievable relative speed (S140), when the speed of the own vehicle is lower than the speed of other vehicles (S50) and the speed of the own vehicle is lower than the difference (Vad-Vrma) between the speed of other vehicles and a target relative speed (S110), and to control the speed of the own vehicle so that the relative speed of the own vehicle with respect to other vehicles becomes an achievable relative speed (Vrmaa) while exploring a space greater than the corrected minimum length on the lane at the lane change destination (S150).

[0020] In the above description, other objects, other features and incidental advantages of the present invention can be easily understood from the description of the embodiments of the present invention described below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Features, advantages, and technical and industrial significance of exemplary embodiments of the present invention will be described below with reference to the accompanying drawings, in which like reference numerals represent like elements, and in which:

[0022] Figure 1 is a schematic diagram showing the configuration of a lane change assist device according to an embodiment;

[0023] Figure 2 is a flowchart corresponding to the lane change assist control program in the embodiment;

[0024] Figure 3 is a diagram showing a map for calculating a reference length Lsre as the minimum length of a space on a lane at a lane change destination required for the own vehicle to change lanes based on the vehicle speed Vad of another vehicle at the lane change destination;

[0025] Figure 4 is a diagram showing a map for calculating the magnitude Vrma of the maximum relative speed when searching for a lane change destination space based on the magnitude Gxma of the permissible acceleration / deceleration;

[0026] Figure 5A A diagram showing a situation in which the own vehicle changes lanes between the preceding vehicle and the following vehicle in a case in which the preceding vehicle traveling in the lane of the lane change destination is slower than the own vehicle;

[0027] Figure 5B A diagram showing a situation in which the own vehicle changes lanes between the preceding vehicle and the following vehicle in a case in which the preceding vehicle traveling in the lane of the lane change destination is slower than the own vehicle;

[0028] Fig. 6A A diagram showing a situation in which the own vehicle changes lanes between the preceding vehicle and the following vehicle in a case in which the following vehicle traveling in the lane of the lane change destination is faster than the own vehicle; and

[0029] Figure 6B This diagram shows a situation in which the own vehicle changes lanes between the preceding vehicle and the following vehicle, in a case in which the following vehicle traveling in the lane of the lane change destination is faster than the own vehicle. DETAILED DESCRIPTION

[0030] Hereinafter, a lane change assist device according to an embodiment of the present invention will be described in detail with reference to the drawings.

[0031] like Figure 1As shown, the lane change assist device 100 according to the embodiment of the present invention is applied to a vehicle 102, and includes a driving assist ECU 10. The vehicle 102 is a vehicle capable of automatic driving, and is provided with a drive ECU 20, a brake ECU 30, an electric power steering ECU 40, and an instrument ECU 50. ECU refers to an Electronic Control Unit (electronic control unit, ECU) having a microcomputer as a main part. In addition, in the following description, the electric power steering is referred to as EPS.

[0032] The microcomputer of each ECU includes a Central Processing Unit (CPU), ReadOnly Memory (ROM), Random Access Memory (RAM), a readable and writable non-volatile memory (N / M), and an interface (I / F). The CPU implements various functions by executing commands (programs, routines) stored in the ROM. Moreover, these ECUs are connected to each other via the Controller Area Network (CAN) 104 so that data can be exchanged (communication can be performed). Therefore, the detection values ​​of sensors (including switches) connected to a specific ECU are also sent to other ECUs.

[0033] The driving assistance ECU 10 is a central control device that performs driving assistance control such as lane change assistance control and lane keeping control. In the embodiment, the driving assistance ECU 10 cooperates with other ECUs to perform lane change assistance control of the vehicle 102 as will be described in detail later.

[0034] The driving support ECU 10 is connected to a camera sensor 12, a radar sensor 14, and a setting operator 16. The camera sensor 12 and the radar sensor 14 include a plurality of camera devices and a plurality of radar devices, respectively. The camera sensor 12 and the radar sensor 14 function as an object information acquisition device 18 that acquires object information around the vehicle 102.

[0035] Although not shown, each camera device of the camera sensor 12 includes a camera unit for photographing the surroundings of the vehicle 102 and a recognition unit for analyzing the image data photographed by the camera unit to recognize objects (object targets) such as white lines on the road and other vehicles. The recognition unit provides information related to the recognized object to the driving assistance ECU 10 at predetermined intervals.

[0036] Each radar device of the radar sensor 14 is equipped with a radar transceiver and a signal processing unit (not shown). The radar transceiver transmits radio waves in the millimeter wave band (hereinafter referred to as "millimeter waves") and receives millimeter waves (i.e., reflected waves) reflected by three-dimensional objects (such as other vehicles, bicycles, etc.) within the transmission range. The signal processing unit provides the driving assistance ECU 10 with information indicating the distance between the own vehicle and the three-dimensional object, the relative speed between the own vehicle and the three-dimensional object, and the relative position (direction) of the three-dimensional object relative to the own vehicle at predetermined intervals based on the phase difference between the transmitted millimeter waves and the received reflected waves, the attenuation level of the reflected waves, and the time from the transmission of the millimeter waves to the reception of the reflected waves. In addition, Light Detection And Ranging (LiDAR) can also be used instead of the radar sensor 14 or in addition to the radar sensor 14.

[0037] Set the operator 16 as Figure 1 The steering wheel shown in the figure is arranged in a position where it can be operated by the driver, and is operated by the driver. Figure 1 Although not shown, the setting operator 16 includes a lane change assist switch. As described in detail later, when the lane change assist switch is turned on and a predetermined condition described later is satisfied, the driving assistance ECU 10 starts the lane change assist control.

[0038] The drive ECU 20 is connected to a drive device 22 that accelerates the vehicle 102 by applying a driving force to a drive wheel 24. The drive ECU 20 normally controls the drive device 22 so that the driving force generated by the drive device 22 changes according to a driving operation performed by the driver, and when receiving a command signal from the driving assistance ECU 10, controls the drive device 22 based on the command signal.

[0039] The brake ECU 30 is connected to a brake device 32 that decelerates the vehicle 102 by applying a braking force to the wheels 34. The brake ECU 30 normally controls the brake device 32 so that the braking force generated by the brake device 32 changes according to the brake operation performed by the driver. When receiving a command signal from the driving assistance ECU 10, the brake ECU 30 performs automatic braking by controlling the brake device 32 based on the command signal. In addition, when the braking force is applied to the wheels, Figure 1 The brake lights (not shown) are illuminated.

[0040] The EPS·ECU40 is connected to an EPS device 42. The EPS·ECU40 controls the EPS device 42 in a manner known in the art based on the steering torque Ts and the vehicle speed Vo detected by the driving operation sensor 60 and the vehicle state sensor 70 described later, thereby controlling the steering assist torque and reducing the steering burden of the driver. In addition, the EPS·ECU40 can steer the steering wheel 44 as needed by controlling the EPS device 42. Thus, the EPS·ECU40 and the EPS device 42 function as an automatic steering device that automatically steers the steering wheel as needed.

[0041] As apparent from the above description, the drive ECU 20 , the drive device 22 , the brake ECU 30 , the brake device 32 , the EPS·ECU 40 , and the EPS device 42 function as the travel control device 90 that controls the vehicle 102 such as braking, driving, and turning.

[0042] A touch panel type display 52 for displaying the status of control performed by the driving assistance ECU 10 is connected to the meter ECU 50. The display 52 may be, for example, a multi-information display for displaying meters and various information, or may be a display of a navigation device 80 described later. As described later, when receiving a signal from the driving assistance ECU 10, the display 52 displays the status of the lane change assistance control.

[0043] The driving operation sensor 60 and the vehicle state sensor 70 are connected to the CAN 104. The information detected by the driving operation sensor 60 and the vehicle state sensor 70 (referred to as sensor information) is sent to the CAN 104. The sensor information sent to the CAN 104 can be used appropriately in each ECU. In addition, the sensor information may be information of a sensor connected to a specific ECU, and the sensor information may be sent from the specific ECU to the CAN 104.

[0044] The driving operation sensor 60 includes a driving operation amount sensor for detecting the operation amount of the accelerator pedal, a braking operation amount sensor for detecting the master cylinder pressure or the pedal force on the brake pedal, etc. In addition, the driving operation sensor 60 includes a steering angle sensor for detecting the steering angle θ, a steering torque sensor for detecting the steering torque Ts, etc. The driving operation sensor 60 also includes a lane change lever operated when the driver wants to change lanes, and a mode switch for switching the driving mode of the vehicle 102 between a sport mode and a comfort mode. In addition, the sport mode is a mode that places more emphasis on the handling responsiveness of the vehicle than on the ride comfort, and the comfort mode is a mode that places more emphasis on the ride comfort than on the handling responsiveness of the vehicle.

[0045] The vehicle state sensor 70 includes a vehicle speed sensor for detecting the vehicle speed Vo of the vehicle 102, a longitudinal acceleration sensor for detecting the acceleration in the longitudinal direction of the vehicle, a lateral acceleration sensor for detecting the lateral acceleration of the vehicle, and a yaw rate sensor for detecting the yaw rate of the vehicle.

[0046] Furthermore, the navigation device 80 is also connected to the CAN 104. The navigation device 80 includes a GPS receiver for detecting the position of the vehicle 102, a storage device for storing map information and road information, and a communication device for obtaining the latest information of the map information and road information from the outside. The navigation device 80 functions as a device for obtaining information of the current position of the vehicle 102, and outputs a signal indicating the current position of the vehicle on the map to the driving assistance ECU 10. Furthermore, when a destination is input to the navigation device 80, it determines a target route from the current position of the vehicle 102 to the destination, and guides the vehicle along the target route. In particular, when there is a branch point (fork point) in front of the vehicle and the vehicle needs to change lanes in front of the branch point in order to travel along the target route, the navigation device 80 displays the need for lane change on the display 52 to notify the driver, and notifies the driving assistance ECU 10.

[0047] In the embodiment, the ROM of the driving assistance ECU 10 stores Figure 2 The flowchart shown corresponds to a lane change assist control program. The CPU of the driving assistance ECU 10 performs lane change assistance by executing the lane change assist control according to the program.

[0048] Lane Change Assist Control

[0049] Next, refer to Figure 2 The flowchart shown in the figure illustrates the lane change assist control procedure in the embodiment. Figure 2 The “lane change assist control” in the flowchart shown is started by the CPU of the driving assistance ECU 10 when the lane change assist switch is turned on, the lane change lever is operated, or a signal indicating that a lane change is required is input from the navigation device 80, and is repeatedly executed at predetermined time intervals.

[0050] First, in S10, the CPU estimates the speed Vad of the other vehicle based on the change in the positional relationship between the other vehicle at the lane change destination and the own vehicle 102 obtained by the object mark information acquisition device 18 and the speed Vo of the own vehicle. Figure 3 The mapping shown in FIG. 1 calculates the reference length Lsre as the minimum length of the space on the lane at the lane change destination required for the vehicle to change lanes. Figure 3As shown, the reference length Lsre is calculated so that the reference length Lsre becomes larger as the vehicle speed Vad of the other vehicle becomes larger.

[0051] For example, Figure 5A , 5B and Fig. 6A , 6B The preceding vehicle 112 and the following vehicle 114 traveling in the lane 110 of the lane change destination are slower than the own vehicle 102 and faster than the own vehicle 102, respectively, and the situation in which the own vehicle changes lanes between the preceding vehicle and the following vehicle is shown. In particular, Figure 5A and Fig. 6A It shows the situation before the lane change. Figure 5B and Figure 6B The situation after the lane change is shown.

[0052] If there is a large space in the lane at the destination of the lane change, there is no need to search for space. However, if there is a small space in the lane at the destination of the lane change, it is necessary to search for space, and consider making a lane change in a manner that ensures the minimum inter-vehicle distance Lmin between the own vehicle 102 and the preceding vehicle 112 and the following vehicle 114 when the lane change is completed.

[0053] from Figure 5B and Figure 6B It can be seen that if the length of the vehicle 102 is set to Lv, the lane change cannot be performed when there is no space greater than 2Lmin+Lv on the lane of the lane change destination. Therefore, the reference length Lsre can be 2Lmin+Lv. Figure 3 As shown, the reference length Lsre is calculated such that the reference length Lsre becomes larger as the speed Vad of the other vehicles increases. In addition, when there are a leading vehicle 112 and a following vehicle 114 in the lane 110 of the lane change destination, and the leading vehicle 112 and the following vehicle 114 have different speeds, the speed Vad may be the average of the speeds of the two vehicles.

[0054] In S20, the CPU estimates the length Ls of the space on the lane of the lane change destination in the area where the host vehicle 102 may be able to change lanes based on the information of the lane change destination obtained by the object mark information acquisition device 18. Furthermore, the CPU determines whether the length Ls of the space is greater than the reference length Lsre, that is, whether the lane change can be made without searching the space. When the CPU makes a positive determination, the control proceeds to S170, and when the CPU makes a negative determination, the control proceeds to S30.

[0055] In S30, the CPU sets the permissible acceleration / deceleration magnitude Gxma of the own vehicle based on the driving condition of the own vehicle, that is, the maximum value of the permissible front and rear acceleration / deceleration magnitude of the own vehicle. In the embodiment, the driving condition of the own vehicle is the distance Ld from the current position of the own vehicle 102 to the branch point Pbp (refer to Figure 5A and Fig. 6A ), the driving mode of the own vehicle, and at least one of the types of lane change requests. The magnitude of the permissible acceleration / deceleration Gxma is set to a value that is larger as the distance Ld is smaller, and when the driving mode is the sport mode, Gxma is set to a larger value than when the driving mode is the comfort mode. Furthermore, when the lane change request is a request of the driver (operation of the lane change lever), the magnitude of the permissible acceleration / deceleration Gxma is set to a larger value than when the lane change request is a request of the navigation device 80 (control request).

[0056] In S40, the CPU determines the acceleration / deceleration value Gxma based on the allowable acceleration / deceleration value. Figure 4 The map shown calculates the maximum relative speed Vrma when searching the space of the lane change destination. The maximum relative speed Vrma is the maximum value of the relative speed Vr (=Vo-Vad) of the own vehicle 102 to other vehicles at the lane change destination.

[0057] Next, the relationship between the permissible acceleration / deceleration magnitude Gxma and the maximum relative speed magnitude Vrma is: Figure 4 The reason for the relationship shown is explained.

[0058] The acceleration and deceleration (acceleration and deceleration) of the own vehicle 102 is Gxo. Figure 4 and Figure 5A In the illustrated situation, the distance Lr by which the own vehicle is relatively displaced with respect to the other vehicle until the vehicle speed Vo of the own vehicle becomes the vehicle speed Vad of the other vehicle by decelerating and accelerating the own vehicle is expressed by the following equation (1).

[0059] Lr=Vr*Vr / (2*Gxo)…(1)

[0060] exist Figure 5A , Figure 5BIn the situation shown, in order to make the inter-vehicle distance between the own vehicle 102 and the preceding vehicle 112 after the lane change to be greater than the minimum inter-vehicle distance Lmin, it is necessary to start decelerating the own vehicle when the inter-vehicle distance between the own vehicle 102 and the preceding vehicle 112 is greater than Lmin-Lr. In addition, in order to make the inter-vehicle distance between the own vehicle 102 and the following vehicle 114 after the lane change to be greater than the minimum inter-vehicle distance Lmin, it is necessary to start decelerating the own vehicle when the inter-vehicle distance between the own vehicle 102 and the following vehicle 114 is greater than Lmin+Lr.

[0061] In addition, sometimes when the own vehicle starts a lane change in front of the preceding vehicle at the lane change destination, the inter-vehicle distance between the own vehicle and the preceding vehicle after the lane change becomes too small. Therefore, in order to make the inter-vehicle distance between the own vehicle and the preceding vehicle after the lane change the minimum inter-vehicle distance Lmin, the inter-vehicle distance between the own vehicle and the preceding vehicle at the start of the lane change needs to be greater than Lfront. Lfront is a value that decreases as the relative speed Vr increases, and can be 0 when the own vehicle makes an action to change lanes.

[0062] When Lmin-Lr is less than Lfront, the distance between the vehicle and the preceding vehicle at the start of the lane change is Lfront. Therefore, the distance between the vehicle and the preceding vehicle after the lane change is Lfront+Lr, which is greater than Lmin. Therefore, the vehicle cannot change lanes to a space with a length of 2Lmin+Lv.

[0063] In order for the vehicle to change lanes to a space of length 2Lmin+Lv, Lfront must be greater than Lmin-Lr. Assuming that Lfront is equal to Lmin-Lr, the following equation (2) holds true based on the above equation (1), so the relative speed Vr is expressed by the following equation (3).

[0064] Lfront=Lmin-Lr

[0065] =Lmin-Vr*Vr / (2*Gxo)…(2)

[0066] Vr={(Lmin-Lfront)*2*Gxo} 1 / 2 …(3)

[0067] exist Fig. 6A , Figure 6BIn the situation shown, in order to make the inter-vehicle distance between the own vehicle 102 and the preceding vehicle 112 after the lane change to be greater than the minimum inter-vehicle distance Lmin, it is necessary to start accelerating the own vehicle when the inter-vehicle distance between the own vehicle 102 and the preceding vehicle 112 is greater than Lmin+Lr. In addition, in order to make the inter-vehicle distance between the own vehicle 102 and the following vehicle 114 after the lane change to be greater than the minimum inter-vehicle distance Lmin, it is necessary to start accelerating the own vehicle when the inter-vehicle distance between the own vehicle 102 and the following vehicle 114 is greater than Lmin-Lr.

[0068] In addition, sometimes when the own vehicle starts a lane change while traveling behind a subsequent vehicle at the destination of the lane change, the inter-vehicle distance between the own vehicle and the subsequent vehicle after the lane change becomes too small. Therefore, in order to make the inter-vehicle distance between the own vehicle and the subsequent vehicle after the lane change the minimum inter-vehicle distance Lmin, the inter-vehicle distance between the own vehicle and the subsequent vehicle at the start of the lane change needs to be greater than Lrear. Lrear is a value that decreases as the relative speed Vr increases, and may be 0 when the own vehicle makes an action to change lanes.

[0069] When Lmin-Lr is less than Lrear, the distance between the vehicle and the following vehicle at the start of the lane change is Lrear. Therefore, the distance between the vehicle and the following vehicle after the lane change is Lrear+Lr, which is greater than Lmin. Therefore, the vehicle cannot change lanes to a space with a length of 2Lmin+Lv.

[0070] In order for the vehicle to change lanes to a space of length 2Lmin+Lv, Lrear must be greater than Lmin-Lr. Assuming that Lrear is equal to Lmin-Lr, the following equation (4) holds true based on the above equation (1), so the relative speed Vr is expressed by the following equation (5).

[0071] Lrear=Lmin-Lr

[0072] =Lmin-Vr*Vr / (2*Gxo)…(4)

[0073] Vr={(Lmin-Lrear)*2*Gxo} 1 / 2 …(5)

[0074] In the above equations (3) and (5), if Lfront and Lrear are set to 0 respectively and Lfront and Lrear must be greater than Lmin-Lr, the following equation (6) holds. Therefore, the relationship between the allowable acceleration and deceleration Gxma and the maximum relative speed Vrma is: Figure 4 The relationship shown.

[0075] Vr=(Lmin*2*Gxo) 1 / 2 …(6)

[0076] In S50, the CPU determines whether the vehicle speed Vo of the own vehicle 102 is greater than the vehicle speed Vad of other vehicles at the lane change destination, that is, whether the own vehicle is faster than other vehicles at the lane change destination. When the CPU makes a negative determination, the control proceeds to S110, and when the CPU makes an affirmative determination, the control proceeds to S60.

[0077] In S60, the CPU determines whether the vehicle speed Vo of the own vehicle 102 is greater than the sum of the vehicle speed Vad of the other vehicle at the lane change destination and the maximum relative speed Vrma Vad+Vrma. That is, the CPU determines whether the relative speed Vr (=Vo-Vad) of the own vehicle 102 to the other vehicle is greater than the maximum relative speed Vrma. When the CPU makes a negative determination, the control proceeds to S80, and when the CPU makes an affirmative determination, the control proceeds to S70.

[0078] In S70, the CPU determines whether the own vehicle 102 can be decelerated. When the CPU makes a negative determination, the control proceeds to S90, and when the CPU makes a positive determination, the control proceeds to S80. In addition, when the inter-vehicle distance between the own vehicle and the following vehicle in the same lane is less than the reference inter-vehicle distance for deceleration determination, it can be determined that the own vehicle cannot be decelerated. In this case, the reference inter-vehicle distance for deceleration determination can be a positive constant, or it can be variably set in a manner such that "the higher the relative speed of the following vehicle to the own vehicle, the larger the reference inter-vehicle distance".

[0079] In S80, the CPU outputs a command signal to the travel control device 90 so that the relative speed Vr of the own vehicle 102 to other vehicles at the lane change destination becomes -Vrma. Furthermore, the CPU searches for a space longer than the reference length Lsre on the lane at the lane change destination while controlling the speed of the own vehicle.

[0080] In S90, the CPU determines the magnitude Vrmad of the relative speed that can be achieved by the own vehicle 102 relative to other vehicles at the lane change destination based on the inter-vehicle distance between the own vehicle 102 and the subsequent vehicle at the lane change destination and the relative vehicle speed of the subsequent vehicle at the lane change destination relative to the own vehicle. In addition, the magnitude Vrmad of the relative speed is smaller than the magnitude Vrma of the maximum relative speed. In addition, based on the magnitude Vrmad of the relative speed, the CPU determines the corrected reference length Lsred as "the corrected minimum length of the space on the lane at the lane change destination required for the own vehicle to change lanes". In this case, the corrected reference length Lsred is determined so that the larger the magnitude Vrmad of the relative speed, the larger the corrected reference length Lsred.

[0081] In S100, the CPU outputs a command signal to the driving control device 90 so that the relative speed Vr of the own vehicle 102 to other vehicles at the lane change destination becomes -Vrmad. Furthermore, the CPU searches for a space longer than the corrected reference length Lsred on the lane at the lane change destination while controlling the speed of the own vehicle.

[0082] In S110, the CPU determines whether the vehicle speed Vo of the own vehicle 102 is less than the difference Vad-Vrma between the vehicle speed Vad of the other vehicle at the lane change destination and the magnitude Vrma of the maximum relative speed. That is, the CPU determines whether the relative speed Vr (=Vo-Vad) of the own vehicle 102 to the other vehicle is less than the sign (positive or negative sign) inversion value -Vrma of the magnitude Vrma of the maximum relative speed. When the CPU makes a negative determination, the control proceeds to S130, and when the CPU makes an affirmative determination, the control proceeds to S120.

[0083] In S120, the CPU determines whether the own vehicle 102 can be accelerated. When the CPU makes a negative determination, the control proceeds to S140, and when the CPU makes an affirmative determination, the control proceeds to S130. In addition, when the inter-vehicle distance between the own vehicle and the preceding vehicle in the same lane is less than the reference inter-vehicle distance for acceleration determination, it can be determined that the own vehicle cannot be accelerated. In this case, the reference inter-vehicle distance for acceleration determination can be a positive constant, or it can be variably set in a manner such that "the higher the relative speed of the preceding vehicle to the own vehicle, the smaller the reference inter-vehicle distance".

[0084] In S130, the CPU outputs a command signal to the travel control device 90 so that the relative speed Vr of the own vehicle 102 to other vehicles at the lane change destination becomes Vrma. Furthermore, the CPU searches for a space longer than the reference length Lsre on the lane at the lane change destination while controlling the speed of the own vehicle.

[0085] In S140, the CPU determines the magnitude Vrmaa of the relative speed that can be achieved by the own vehicle 102 relative to other vehicles at the lane change destination based on the inter-vehicle distance between the own vehicle 102 and the preceding vehicle at the lane change destination and the relative vehicle speed of the preceding vehicle at the lane change destination relative to the own vehicle. In addition, the magnitude Vrmaa of the relative speed is smaller than the magnitude Vrma of the maximum relative speed. In addition, based on the magnitude Vrmaa of the relative speed, the CPU determines the corrected reference length Lsrea as "the corrected minimum length of the space on the lane at the lane change destination required for the own vehicle to change lanes". In this case, the corrected reference length Lsrea is determined so that the larger the magnitude Vrmaa of the relative speed, the larger the corrected reference length Lsrea.

[0086] In S150, the CPU outputs a command signal to the driving control device 90 so that the relative speed Vr of the own vehicle 102 to other vehicles at the lane change destination becomes Vrmaa. Furthermore, the CPU searches for a space longer than the corrected reference length Lsrea on the lane at the lane change destination while controlling the speed of the own vehicle.

[0087] In S160, the CPU determines whether the result of the search in S80, S100, S130 or S150 is "determined that there is a space satisfying each length requirement." If the CPU makes a negative determination, the control proceeds to S180, and if the CPU makes an affirmative determination, the control proceeds to S170.

[0088] In S170, the CPU outputs a command signal to the driving control device 90 so that the vehicle 102 moves to a space that satisfies the length requirement by automatic driving, thereby executing a lane change of the vehicle to the lane of the lane change destination. In addition, the lane change based on automatic driving can be executed in any method known in the technical field.

[0089] In S180, the CPU determines whether a reference time Δt (positive constant) or more has passed since the start of this control. When the CPU makes a negative determination, the CPU temporarily terminates this control and returns this control to S10. When the CPU makes a positive determination, the CPU terminates this control without executing the lane change of the own vehicle, and outputs a command signal to the meter ECU 50, and displays the end of this control on the display 52.

[0090] As can be seen from the above description, according to the embodiment, the reference length Lsre, which is "the minimum length of the space on the lane at the lane change destination required for the own vehicle to change lanes", is calculated in such a way that the reference length Lsre becomes larger as the vehicle speed Vad of other vehicles at the lane change destination increases (S10). The length Ls of the space existing on the lane at the lane change destination is estimated in the area where the own vehicle 102 may be able to change lanes. By determining whether the length Ls of the space is greater than the reference length Lsre, it is determined whether the lane change can be performed without searching the space (S20).

[0091] When the length Ls of the space is less than the reference length Lsre, the permissible acceleration / deceleration magnitude Gxma of the own vehicle is set based on the driving condition of the own vehicle, that is, the maximum value of the permissible front and rear acceleration / deceleration magnitude of the own vehicle (S30). Figure 4 The maximum relative speed Vrma when searching for a lane change destination space is calculated using the map shown (S40).

[0092] Furthermore, while controlling the travel control device 90 to accelerate or decelerate the own vehicle so that the relative speed of the own vehicle to other vehicles reaches the target relative speed, a space longer than or equal to the minimum length existing in the lane of the lane change destination is searched ( S80 , S130 ).

[0093] The magnitude of the permissible acceleration / deceleration Gxma is set to a value that becomes larger as the distance Ld from the current position of the own vehicle 102 to the branch point Pbp becomes smaller. When the driving mode is the sport mode, the magnitude of the permissible acceleration / deceleration Gxma is set to a larger value than when the driving mode is the comfort mode. Furthermore, when the lane change request is a request of the driver (operation of the lane change lever), the magnitude of the permissible acceleration / deceleration Gxma is set to a larger value than when the lane change request is a request of the navigation device 80 (requirement of the vehicle's driving control).

[0094] Thus, the vehicle speed Vo of the own vehicle can be controlled in such a manner that the relative speed Vr (= Vo-Vad) of the own vehicle to other vehicles traveling in the lane of the lane change destination becomes the target relative speed Vrma calculated based on the driving condition of the own vehicle such as the distance Ld from the current position of the own vehicle to the branch point. Therefore, compared with the case where the own vehicle is accelerated or decelerated to explore the space only according to the speed of other vehicles regardless of the driving condition of the own vehicle, the space existing in the lane of the lane change destination required for the own vehicle to change lanes can be appropriately explored.

[0095] In particular, when the speed Vo of the own vehicle 102 is greater than the speed Vad of other vehicles at the lane change destination (S50), and the speed of the own vehicle is less than the sum of the speed of other vehicles and the target relative speed (Vrma+Vrma) (S60), the travel control device 90 is controlled so that the relative speed of the own vehicle to other vehicles becomes the target relative speed to control the speed of the own vehicle, while searching for a space longer than the minimum length Lsre existing in the lane at the lane change destination (S80). Thus, the speed of the own vehicle can be controlled so that the relative speed becomes the target relative speed while searching for a space longer than the minimum length.

[0096] In contrast, when the speed Vo of the own vehicle 102 is greater than the speed Vad of other vehicles (S50), and the speed of the own vehicle is greater than the sum of the speed of other vehicles and the target relative speed (S60), and the own vehicle cannot be decelerated (S70), the achievable relative speed Vrmad of the own vehicle relative to other vehicles is determined (S90). In addition, the corrected minimum length Lsred of the space in which the own vehicle can change lanes is determined based on the achievable relative speed (S90). Furthermore, while controlling the speed of the own vehicle by controlling the driving control device in such a manner that the relative speed of the own vehicle relative to other vehicles becomes the achievable target relative speed (-Vrmad), the space above the corrected minimum length Lsred existing in the lane of the lane change destination is explored. Thus, the speed of the own vehicle can be controlled in such a manner that the relative speed becomes the achievable target relative speed, while exploring the space above the corrected minimum length.

[0097] In addition, when the speed Vo of the own vehicle 102 is lower than the speed Vad of the other vehicles (S50), and the speed of the own vehicle is greater than the difference between the speed of the other vehicles and the target relative speed (Vad-Vrma) (S110), the travel control device 90 is controlled so that the relative speed of the own vehicle to the other vehicles becomes the target relative speed to control the speed of the own vehicle, while searching for a space greater than the minimum length Lsre existing in the lane of the lane change destination (S130). Thus, the speed of the own vehicle can be controlled so that the relative speed becomes the target relative speed while searching for a space greater than the minimum length.

[0098] On the other hand, when the speed Vo of the own vehicle 102 is lower than the speed Vad of the other vehicle (S50), and the speed of the own vehicle is lower than the difference between the speed of the other vehicle and the target relative speed (Vad-Vrma) (S110), and the own vehicle cannot be accelerated (S120), the achievable relative speed Vrmaa of the own vehicle with respect to the other vehicle is determined (S140). In addition, when the speed Vo of the own vehicle 102 is lower than the speed Vad of the other vehicle (S50), and the speed of the own vehicle is lower than the difference between the speed of the other vehicle and the target relative speed (Vad-Vrma) (S110), and the own vehicle cannot be accelerated (S120), the corrected minimum length Lsrea of ​​the space in which the own vehicle can change lanes is determined based on the achievable relative speed (S140). Furthermore, while controlling the speed of the own vehicle by controlling the driving control device in such a manner that the relative speed of the own vehicle with respect to other vehicles becomes the achievable target relative speed Vrmaa, a space greater than the corrected minimum length Lsrea existing in the lane of the lane change destination is searched (S150). Thus, the speed of the own vehicle can be controlled in such a manner that the relative speed becomes the achievable target relative speed, while a space greater than the corrected minimum length can be searched.

[0099] As mentioned above, although the specific embodiment of the present invention has been described in detail, it is obvious to those skilled in the art that the present invention is not limited to the above-mentioned embodiment, and other various embodiments can be implemented within the scope of the present invention.

[0100] For example, in the above-described embodiment, the reference length Lsre is calculated in S10 so that the reference length Lsre increases as the vehicle speed Vad of the other vehicle at the lane change destination increases. However, the reference length Lsre may be a constant value.

[0101] In addition, in the above-mentioned embodiment, in S30, the magnitude Gxma of the permissible acceleration / deceleration of the own vehicle is set based on the driving condition of the own vehicle. The driving condition of the own vehicle is the distance Ld from the current position of the own vehicle 102 to the branch point, the driving mode of the own vehicle, and the type of lane change request. However, any one of the "distance Ld", "driving mode of the own vehicle", and "type of lane change request" may be omitted.

[0102] Furthermore, in the above-described embodiment, in S70 and S120, it is determined whether the own vehicle 102 can be decelerated and accelerated, respectively. However, these steps may be omitted.

Claims

1. A lane change assist device, comprising: An object information acquisition device that acquires information about object targets around the own vehicle; and Control unit, The control unit is configured as follows: estimating the speed of another vehicle traveling in the lane of the lane change destination based on the information acquired by the object marker information acquisition device; determining a minimum length of a space on a lane at a lane change destination required for the own vehicle to change lanes based on the estimated speed of the other vehicle; estimating an actual length of a space on the lane at the lane change destination based on the information acquired by the object marker information acquisition device; determining whether a lane change of the own vehicle to the lane change destination is possible based on the minimum length and the actual length; The control unit is configured to, when the feasibility determination is not possible, set an allowable acceleration / deceleration of the own vehicle based on the driving condition of the own vehicle, calculate a target relative speed of the own vehicle with respect to the other vehicle based on the allowable acceleration / deceleration, control the speed of the own vehicle so that the relative speed of the own vehicle with respect to the other vehicle becomes the target relative speed, and explore the space on the lane at the lane change destination required for the own vehicle to change lanes.

2. The lane change assist device according to claim 1, The control unit is configured to control the speed of the own vehicle so that the relative speed of the own vehicle to the other vehicles becomes the target relative speed, while exploring a space longer than the minimum length on the lane of the lane change destination, when the speed of the own vehicle is greater than the speed of the other vehicles and the speed of the own vehicle is less than the sum of the speed of the other vehicles and the target relative speed.

3. The lane change assist device according to claim 1, The control unit is configured to determine an achievable relative speed of the own vehicle with respect to the other vehicles when the speed of the own vehicle is greater than the speed of the other vehicles and the speed of the own vehicle is greater than the sum of the speed of the other vehicles and the target relative speed, determine a corrected minimum length of a space in which the own vehicle can change lanes based on the achievable relative speed, control the speed of the own vehicle in such a way that the relative speed of the own vehicle with respect to the other vehicles becomes the achievable relative speed, and explore a space greater than the corrected minimum length on the lane of the lane change destination.

4. The lane change assist device according to claim 1, The control unit is configured to control the speed of the own vehicle so that the relative speed of the own vehicle with respect to the other vehicle becomes the target relative speed, while exploring a space longer than the minimum length on the lane of the lane change destination, when the speed of the own vehicle is lower than the speed of the other vehicle and the speed of the own vehicle is higher than the difference between the speed of the other vehicle and the target relative speed.

5. The lane change assist device according to claim 1, The control unit is configured to determine an achievable relative speed of the own vehicle with respect to the other vehicle when the speed of the own vehicle is lower than the speed of the other vehicle and the speed of the own vehicle is lower than the difference between the speed of the other vehicle and the target relative speed, determine a corrected minimum length of a space in which the own vehicle can change lanes based on the achievable relative speed, control the speed of the own vehicle so that the relative speed of the own vehicle with respect to the other vehicle becomes the achievable relative speed, and explore a space longer than the corrected minimum length on the lane at the lane change destination.

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