Lane Change Assistance Device
Patent Information
- Application Number
- DE102024128283
- Authority / Receiving Office
- DE · DE
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2023-10-04
- Filing Date
- 2024-09-30
- Publication Date
- 2025-04-10
Smart Images
Figure 00000000_0000_ABST
Abstract
Description
BACKGROUND OF THE INVENTION1. Field of the InventionThe present invention relates to a lane change assist device for a vehicle such as an automobile.2. Description of Related ArtAmong the lane change assist devices, a lane change assist device that determines whether lane change of an own vehicle is possible and, when lane change of the own vehicle is not possible, controls a vehicle speed of the own vehicle to search a place for lane change on a lane of a lane change destination is known.For example, Japanese Patent Application JP 2021-149 119 A describes a lane change assist device that determines whether or not the lane change of an own vehicle is permitted, and when the lane change is not permitted, accelerates or decelerates the own vehicle according to the speed of another vehicle moving on a lane of a lane change destination, and determines whether or not the lane change of the own vehicle is possible. With this type of lane change assist device, it is possible to efficiently determine whether lane change is possible, compared to a case where the own vehicle is not accelerated or decelerated.SUMMARY OF THE INVENTIONHowever, in the related-art lane change assist device such as the device described in JP 2021-149 119 A, the own vehicle is accelerated or decelerated only according to the speed of the other vehicle traveling on the lane of the lane change target without considering urgency and the like of the lane change. Thus, a space for lane change cannot be searched especially when the speed of the own vehicle is controlled according to a traveling state of the own vehicle such as urgency of lane change.The present invention provides a lane change assist device modified to be capable of preferentially searching a space for lane change by controlling a speed of an own vehicle in accordance with a traveling state of the own vehicle such as urgency of lane change.According to the present invention, there is provided a lane change assist device (100), the lane change assist device (100) comprising: an object target information acquisition device (18) that acquires information on an object target in the vicinity of an own vehicle (102); and a control unit (driving assist ECU 10) configured to estimate a vehicle speed (Vad) of another vehicle (112, 114) that travels on a lane (110) of a lane change target from the information acquired by the object target information acquisition device, based on the estimated vehicle speed of the other vehicle (S 10), a minimum length (Lsre) of a space on the lane of the lane change target required for the own vehicle to perform a lane change, determining an actual length (Ls) of a space on the lane of the lane change target based on the information obtained by the object target information acquisition device, and performing a possibility determination (S 20) that determines whether lane change of the own vehicle to the lane change target is possible based on the minimum length and the actual length.The control unit (driving support ECU 10) is configured to, when the possibility determination is impossible (negative) (S 20), set (S 30) an allowable acceleration or deceleration (Gxma) of the own vehicle based on a traveling state of the own vehicle, calculate (S 40) a target relative speed (Vrma) of the own vehicle with respect to the other vehicle based on the allowable acceleration or deceleration, and search for a space on the lane of the lane change target necessary for the own vehicle to make a lane change while controlling a vehicle speed of the own vehicle such that a relative speed of the own vehicle with respect to the other vehicle becomes this target relative speed (S 80, S 100, S 130, S 150).According to the configuration described above, when the possibility determination is impossible (negative), the allowable acceleration or deceleration of the own vehicle is set based on the traveling state of the own vehicle, and the target relative speed of the own vehicle with respect to the other vehicle is calculated based on the allowable acceleration or deceleration. In addition, the space on the lane of the lane change target required by the own vehicle to perform lane change is searched while controlling the vehicle speed of the own vehicle such that the relative speed of the own vehicle with respect to the other vehicle becomes the target relative speed.Thus, the vehicle speed of the own vehicle can be controlled such that the relative speed of the own vehicle with respect to the other vehicle traveling on the lane of the lane change target becomes the target relative speed calculated in accordance with the traveling state of the own vehicle. That is, as compared with a case where the space is searched while the own vehicle is accelerated or decelerated only according to the speed of the other vehicle, it is preferable to search the space on the lane of the lane change target that the own vehicle needs to make a lane change.In one aspect of the invention, the control unit (driving support ECU 10) is configured to, when the own vehicle speed (Vo) is higher than the other vehicle speed (Vad) (S 50) and the own vehicle speed is equal to or lower than a sum of the other vehicle speed and the target relative speed (Vad+ Vra) (S 60), search for a space equal to or greater than the minimum length on the lane of the lane change target, while controlling the own vehicle speed such that the relative speed of the own vehicle with respect to the other vehicle becomes the target relative speed (S 80).In another aspect of the invention, the control unit (driving support ECU 10) is configured to, when the vehicle speed of the own vehicle is higher than the vehicle speed of the other vehicle (S 50) and the vehicle speed of the own vehicle is higher than a sum of the vehicle speed of the other vehicle and the target relative speed (Vad+ Vra) (S 60), determine a realizable relative speed (Vrmaa) of the own vehicle with respect to the other vehicle, determine a correction minimum length (Lsrea) of a space in which the own vehicle can make a lane change based on the realizable relative speed (S 90), and search for a space equal to or greater than the correction minimum length on the lane of the lane change target, while the vehicle speed of the own vehicle is controlled so that the relative speed of the own vehicle with respect to the other vehicle becomes the realizable relative speed (-Vrmaa) (S100).In another aspect of the invention, the control unit (driving support ECU 10) is configured to, when the vehicle speed of the own vehicle is equal to or less than the vehicle speed of the other vehicle (S 50) and the vehicle speed of the own vehicle is equal to or greater than a difference between the vehicle speed of the other vehicle and the target relative speed (Vad- Vrma) (S 110), search for a space equal to or greater than the minimum length on the lane of the lane change target while controlling the vehicle speed of the own vehicle such that the relative speed of the own vehicle with respect to the other vehicle becomes the target relative speed (S 130).In another aspect of the invention, the control unit (driving support ECU 10) is configured to, when the vehicle speed of the own vehicle is equal to or less than the vehicle speed of the other vehicle (S 50) and the vehicle speed of the own vehicle is less than a difference between the vehicle speed of the other vehicle and the target relative speed (Vad- Vrma) (S 110), determine a realizable relative speed (Vrmaa) of the own vehicle with respect to the other vehicle, determine a correction minimum length Lsrea) of a space in which the own vehicle can perform lane change based on the realizable relative speed (S 140), and search for a space equal to or greater than the correction minimum length on the lane of the lane change target, while the vehicle speed of the own vehicle is controlled so that the relative speed of the own vehicle with respect to the other vehicle becomes the realizable relative speed (Vrmaa) (S 150).In the above description, other objects, features and attendant advantages of the invention will be readily understood from the following detailed description of embodiments of the invention when taken in conjunction with the accompanying drawings.BRIEF DESCRIPTION OF THE FIGURESFeatures, advantages, and technical and industrial significance of exemplary embodiments of the invention will be described below with reference to the accompanying drawings, in which like numerals denote like elements, and in which: FIG. 1 is a schematic configuration diagram illustrating a lane change assist device according to an embodiment; FIG. 2 is a flowchart corresponding to a lane change assist control program in the embodiment; FIG. 3 is a view showing a map for calculating a reference length Lsre as a minimum length of a space on a lane of a lane change target required for an own vehicle to perform lane change based on a vehicle speed Vad of another vehicle in the lane change target; FIG. 4 is a view showing a map for calculating a maximum relative speed amount Vrma when searching the space of the lane change target based on an allowable acceleration or deceleration amount Gxma; FIG. 5A is a view indicating a state in which the own vehicle makes a lane change between a preceding vehicle and a following vehicle when the vehicle speed of the preceding vehicle moving on the lane of the lane change target is lower than the vehicle speed of the own vehicle; FIG. 5B is a view indicating a state in which the own vehicle makes a lane change between the preceding vehicle and the following vehicle when the vehicle speed of the preceding vehicle moving on the lane of the lane change target is lower than the vehicle speed of the own vehicle; FIG. 6A is a view indicating a state in which the own vehicle makes a lane change between the preceding vehicle and the following vehicle in a case where a vehicle speed of the following vehicle moving on the lane of the lane change target is higher than the vehicle speed of the own vehicle; and FIG. 6B is a view indicating a state in which the own vehicle makes a lane change between the preceding vehicle and the following vehicle when the vehicle speed of the following vehicle moving on the lane of the lane change target is higher than the vehicle speed of the own vehicle.DETAILED DESCRIPTION OF THE EMBODIMENTSA lane change assist device according to an embodiment of the invention will be described below with reference to the accompanying drawings.As illustrated in FIG. 1, a lane change assist device 100 according to the embodiment of the invention is applied to a vehicle 102 and includes a driving assist ECU 10. The vehicle 102, which is a vehicle capable of autonomous driving, includes a driving ECU 20, a brake ECU 30, an electric power steering ECU 40, and a meter ECU 50. By ECU, it is meant an electronic control unit (ECU) including a microcomputer as a main component. Note that in the following description, the electronic power steering is referred to as EPS.The microcomputer of each control device includes a central processing unit (CPU), a read only memory (ROM), a random access memory (RAM), a readable and writable nonvolatile memory (N / M), an interface (I / F), and the like. The CPU performs various kinds of functions by executing instructions (programs, routines) stored in the ROM. In addition, the controllers are connected to each other so that they can communicate (communicate) via a controller area network (CAN) 104. Thus, a detection value and the like of a sensor (including a switch) connected to a certain control device is also transmitted to other control devices.The driving support ECU 10 is a central control device that performs driving support control such as lane change support control and lane keeping control. In the embodiment, the driving support ECU 10 executes the lane change support control of the vehicle 102 in cooperation with other ECUs, as will be described in detail later.A camera sensor 12, a radar sensor 14, and a setting actuator 16 are connected to the driving support ECU 10. The camera sensor 12 and the radar sensor 14 each include a plurality of camera devices and a plurality of radar devices. The camera sensor 12 and the radar sensor 14 function as an object target information acquisition device 18 that acquires object target information around the vehicle 102.Each camera device of the camera sensor 12 includes a camera unit that captures an image around the vehicle 102, and a recognition unit that analyzes the image data obtained by capturing the camera unit to recognize object targets such as white lines and other vehicles on a road. The recognition unit supplies information on the recognized object targets to the driving support ECU 10 for each predetermined period.Each radar device of radar sensor 14 includes a radar transmitting and receiving unit and a signal processing unit (not shown). The radar transmitting and receiving unit radiates a radio wave of a millimeter wave band (hereinafter referred to as a "millimeter wave") and receives a millimeter wave (i.e., a reflected wave) reflected from a three-dimensional object (such as another vehicle and a bicycle) located in a radiation area. The signal processing unit supplies, to the driving support ECU 10, information representing a distance between the own vehicle and the three-dimensional object, a relative speed between the own vehicle and the three-dimensional object, a relative position (direction) of the three-dimensional object with respect to the own vehicle, and the like for each predetermined period, based on a phase difference between the transmitted millimeter wave and the received reflected wave, a degree of attenuation of the reflected wave, a period from transmission of the millimeter wave to reception of the reflected wave, and the like. Note that a LiDAR (Light Detection and Ranging) may be used instead of or in addition to the radar sensor 14.The adjustment actuator 16 is provided at a location where a driver can operate the adjustment actuator 16 like a steering wheel not illustrated in FIG. 1 and is operated by the driver. The adjustment actuator 16 includes a lane change assist switch, which is not illustrated in FIG. 1. As described later in detail, the driving support ECU 10 starts the lane change support control when the lane change support switch is in an ON state and a predetermined condition described later is satisfied.A driving device 22 that accelerates the vehicle 102 by applying driving force to a driving wheel 24 is connected to the travel ECU 20. The driving ECU 20 controls the driving device 22 so that the driving force to be generated by the driving device 22 changes depending on the driving operation by the driver in normal times, and when a command signal is received from the driving support ECU 10, controls the driving device 22 based on the command signal.Connected to the brake ECU 30 is a brake device 32 that decelerates the vehicle 102 by braking by applying a braking force to a wheel 34. The brake ECU 30 controls the brake device such that the braking force to be generated by the brake device 32 changes depending on the brake operation by the driver in normal times. When a command signal is received from the driving support ECU 10, the brake ECU 30 performs autonomous braking by controlling the brake device 32 based on the command signal. Note that a brake lamp not illustrated in FIG. 1 lights up when the braking force is transmitted to the wheel.An EPS device 42 is connected to the EPS ECU 40. The EPS ECU 40 controls a steering assist torque by controlling the EPS device 42 in a manner well known in the art based on a steering torque Ts and a vehicle speed Vo that is detected by a drive operation sensor 60 and a vehicle state sensor 70 described later and reduces the steering load of the driver. Moreover, the EPS ECU 40 may steer a steering wheel 44 as needed by controlling the EPS device 42. Thus, the EPS ECU 40 and the EPS device 42 function as an automatic steering device that automatically steering the steering wheel as needed.As is apparent from the above description, the travel 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 a travel control device 90 that controls travel operations such as braking and travel, and turning of the vehicle 102.Connected to the meter ECU 50 is a touch panel display 52 that displays a state of control and the like by the driving support ECU 10. The display 52 may be a multi-information display on which counters and various kinds of information are displayed, for example, or may be a display of a navigation device 80 described later. As described later, the display 52 displays a state of the lane change assist control when a signal is received from the driving assist ECU 10.The drive operation sensor 60 and the vehicle state sensor 70 are connected to the CAN 104. The information (referred to as sensor information) detected by the drive operation sensor 60 and the vehicle state sensor 70 is transmitted to the CAN 104. The sensor information transmitted to the CAN 104 may be used in each controller accordingly. Note that the sensor information is information of a sensor connected to a specific controller, and may be transmitted from the respective controller to the CAN 104.The drive operation sensor 60 includes a travel operation amount sensor that detects an operation amount of an accelerator pedal, a brake operation amount sensor that detects a master cylinder pressure or a pedal force with respect to a brake pedal, and the like. Further, the drive operation sensor 60 includes a steering angle sensor that detects a steering angle θ, a steering torque sensor that detects a steering torque Ts, and the like. In addition, the drive operation sensor 60 includes a turning lever to be operated when the driver desires to make a lane change, and a mode switch that switches the driving mode of the vehicle 102 between a sport mode and a comfort mode. Note that the sport mode is a mode in which the responsiveness of the control of the vehicle is more important than the ride comfort, and the comfort mode is a mode in which the ride comfort is more important than the responsiveness of the control of the vehicle.The vehicle state sensor 70 includes a vehicle speed sensor that detects the vehicle speed Vo of the vehicle 102, a front-rear acceleration sensor that detects the acceleration in a front-rear direction of the vehicle, a lateral acceleration sensor that detects the acceleration in a lateral direction of the vehicle, a yaw rate sensor that detects the yaw rate of the vehicle, and the like.Further, the navigation device 80 is also connected to the CAN 104. The navigation device 80 includes a GPS receiver that detects a position of the vehicle 102, a storage device that stores map information and road information, and a communication device that acquires, from the outside, current information of the map information and the road information. The navigation device 80 functions as a device that acquires information on the current location of the vehicle 102 and outputs a signal indicating the current location of the vehicle on the map to the driving support ECU 10. When a destination is input, the navigation device 80 determines a destination route from the current location of the vehicle 102 to the destination, and guides the vehicle to travel along the destination route. Specifically, when there is a branch point in front of the vehicle and the vehicle needs to make a lane change in front of the branch point to travel the target route, the navigation device 80 displays on the display 52 that the vehicle needs to make a lane change to notify the driver, and also notifies the driving support ECU 10.In the embodiment, the ROM of the driving support ECU 10 stores a lane change support control program according to the flowchart illustrated in FIG. 2. The CPU of the driving support ECU 10 executes the lane change support control in accordance with the program.Lane Change Assist ControlThe lane change assist control program in the embodiment will be described below with reference to a flowchart illustrated in FIG. 2. The lane change assist control in the flowchart illustrated in FIG. 2 is started by the CPU of the driving assist ECU 10 when the shift lever is operated or when a signal indicating that a lane change is required is input from the navigation device 80 in a state where the lane change assist switch is in an ON state, and is repeatedly executed for each predetermined period.First, in S 10, the CPU estimates a vehicle speed Vad of the other vehicle in the lane change target based on the change of a positional relationship between the other vehicle detected by the object target information detection device 18 and the own vehicle 102 and a vehicle speed Vo of the own vehicle. In addition, from the map illustrated in FIG. 3, the CPU calculates, from the vehicle speed Vad of the other vehicle, a reference length Lsre as a minimum length of a space on a lane of the lane change target required for the own vehicle to perform lane change. As illustrated in FIG. 3, the reference length Lsre is calculated to be larger the higher the vehicle speed Vad of the other vehicle is.For example, FIGS. 5A and 5B and FIGS. 6A and 6B illustrate states in which the own vehicle makes a lane change between a preceding vehicle and a following vehicle, respectively, in a case where the vehicle speeds of the preceding vehicle 112 and the following vehicle 114 moving on a lane 110 of the lane change target are lower than the vehicle speed of the own vehicle 102 and in a case where the vehicle speeds of the preceding vehicle 112 and the following vehicle 114 moving on the lane 110 of the lane change target are higher than the vehicle speed of the own vehicle 102. Specifically, FIGS. 5A and 6A show the state before lane change, and FIGS. 5B and 6B show the state after lane change.In a case where there is a large space on the lane of the lane change target, it is not necessary to search for a space. However, in a case where the space on the lane of the lane change target is small, it is necessary to search for a space, and it is attempted to perform lane change such that a minimum inter-vehicle distance Lmin between the own vehicle 102 and the preceding vehicle 112 and between the own vehicle 102 and the following vehicle 114 is ensured, respectively, when the lane change is completed.As can be seen from FIGS. 5B and 6B, when a length of the own vehicle 102 is set to be Lv, the own vehicle 102 can make a lane change only when there is a space on the lane of the lane change target that is equal to or greater than 2Lmin+Lv. The reference length Lsre can thus be 2Lmin+Lv. As illustrated in FIG. 3, the reference length Lsre is calculated to be larger the higher the vehicle speed Vad of the other vehicle is. Note that in a case where there are the preceding vehicle 112 and the following vehicle 114 on the lane 110 of the lane change target and the vehicle speeds of the two vehicles are different, the vehicle speed Vad may be an average value of the vehicle speeds of the two vehicles.In S 20, based on the information on the lane change target acquired by the object target information acquisition device 18, the CPU estimates a length Ls of the space in the lane of the lane change target in a range in which the own vehicle 102 is likely to make a lane change. In addition, the CPU determines whether or not the length Ls of the space is equal to or greater than the reference length Lsre, i.e., whether or not a lane change is possible without searching for a space. If the determination result is positive, the CPU proceeds to the current control after S 170, and if the determination result is negative, the CPU proceeds to the current control after S 30.In S 30, the CPU sets a magnitude Gxma of the own vehicle allowable acceleration or deceleration, i.e., a maximum value of a magnitude of the forward-rearward acceleration or deceleration allowable for the own vehicle, based on a traveling state of the own vehicle. In the embodiment, the traveling state of the own vehicle is at least one of a distance Ld from the current location of the own vehicle 102 to a branch point Pbp (see FIGS. 5A and 6A ), a traveling mode of the own vehicle, or a type of lane change request. The allowable acceleration or deceleration amount Gxma is set to a larger value when the distance Ld is smaller and is set to a larger value when the driving mode is the sport mode than when the driving mode is the comfort mode. Further, the allowable acceleration or deceleration amount Gxma is set to a larger value when the lane change request is a driver's request (operation of the steering lever) than when the lane change request is a navigation device 80 request (control request).In S 40, the CPU calculates a maximum relative speed amount Vrma when the space in the lane change target is searched from the map illustrated in FIG. 4 based on the allowable acceleration or deceleration amount Gxma. The maximum relative speed amount Vrma is a maximum value of the amount of a relative speed Vr (Vo-Vad) of the own vehicle 102 with respect to the other vehicle in the lane change target.A reason why a relationship between the allowable acceleration or deceleration magnitude Gxma and the maximum relative speed magnitude Vrma becomes a relationship illustrated in FIG. 4 will be described below.In the states illustrated in FIGS. 4 and 5A, a distance Lr that the own vehicle is displaced relative to the other vehicle until the vehicle speed Vo of the own vehicle becomes the vehicle speed Vad of the other vehicle by deceleration and acceleration of the own vehicle is expressed by the following expression (1), wherein the acceleration or deceleration of the own vehicle 102 is Gxo.In the states illustrated in FIGS. 5A and 5B, in order to make an inter-vehicle distance between the own vehicle 102 and the preceding vehicle 112 after the lane change equal to or greater than the minimum inter-vehicle distance Lmin, it is necessary to start deceleration of the own vehicle in a state in which the inter-vehicle distance between the own vehicle 102 and the preceding vehicle 112 is equal to or greater than Lmin-Lr. In order for the inter-vehicle distance between the own vehicle 102 and the preceding vehicle 114 after the lane change to be equal to or greater than the minimum inter-vehicle distance Lmin, the deceleration of the own vehicle needs to start in a state in which the inter-vehicle distance between the own vehicle 102 and the preceding vehicle 114 is equal to or greater than Lmin+Lr.When the lane change is started in a state where the own vehicle is preceding the preceding vehicle in the lane change target, the inter-vehicle distance between the own vehicle and the preceding vehicle after the lane change may become too small. In order for the inter-vehicle distance between the own vehicle and the preceding vehicle after the lane change to correspond to 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 equal to or greater than Lfront. Lfront is a value that is smaller the higher the relative speed Vr is, and that may be 0 when the own vehicle starts moving for the lane change.In a case where Lmin-Lr is smaller than Lfront, the inter-vehicle distance between the own vehicle and the preceding vehicle at the start of the lane change is Lfront, and thus the inter-vehicle distance between the own vehicle and the preceding vehicle after completion of the lane change becomes Lfront+Lr, which is larger than Lmin. Therefore, the own vehicle cannot make a lane change to a space having a length of 2Lmin+Lv.In order for the own vehicle to make a lane change into the space having a length of 2Lmin+Lv, Lfrontmust be equal to or greater than Lmin-Lr. When Lfront is Lmin-Lr, the following expression (2) is expressed by the expression (1), and thus the relative speed Vr is expressed by the following expression (3).In the states illustrated in FIGS. 6A and 6B, the acceleration of the own vehicle needs to be started in a state where the inter-vehicle distance between the own vehicle 102 and the preceding vehicle 112 after the lane change is equal to or greater than the minimum inter-vehicle distance Lmin. In order for the inter-vehicle distance between the own vehicle 102 and the preceding vehicle 114 after the lane change to be equal to or greater than the minimum inter-vehicle distance Lmin, the acceleration of the own vehicle needs to be started in a state in which the inter-vehicle distance between the own vehicle 102 and the preceding vehicle 114 is equal to or greater than Lmin-Lr.When the own vehicle starts the lane change in a state where the own vehicle starts traveling behind the following vehicle in the lane change destination, the inter-vehicle distance between the own vehicle and the following vehicle after the lane change may become too small. In order for the inter-vehicle distance between the own vehicle and the following vehicle after the lane change to correspond to the minimum inter-vehicle distance Lmin, the inter-vehicle distance between the own vehicle and the following vehicle at the start of the lane change needs to be equal to or greater than Learn. Learn is a value that decreases as the relative speed Vr increases, and may be 0 when the own vehicle is moving to perform a lane change.In a case where Lmin-Lr is smaller than Lrear, the inter-vehicle distance between the own vehicle and the following vehicle becomes Lrear at the start of the lane change, and thus the inter-vehicle distance between the own vehicle and the following vehicle becomes Lrear+Lr after completion of the lane change, which is larger than Lmin. Therefore, the own vehicle cannot make a lane change to a space having a length of 2Lmin+Lv.In order for the own vehicle to make a lane change into the space having a length of 2Lmin+Lv, Learmust be equal to or greater than Lmin-Lr. When Lrear is Lmin-Lr, the following expression (4) is expressed by the expression (1), and thus the relative speed Vr is expressed by the following expression (5).In Expressions (3) and (5), when Lfront and Lrear are set to 0 and Lfront and Lrear are required to be equal to or greater than Lmin-Lr, the following Expression (6) holds. Thus, a relationship is established between the allowable acceleration or deceleration magnitude Gxma and the maximum relative speed magnitude Vrma as shown in FIG. 4.In S 50, the CPU determines whether or not the vehicle speed Vo of the own vehicle 102 is higher than the vehicle speed Vad of the other vehicle in the lane change target, i.e., whether or not the own vehicle is faster than the other vehicle in the lane change target. The CPU continues the current control to S 110 when a negative determination result is obtained, and continues the current control to S 60 when a positive determination result is obtained.In S 60, the CPU determines whether or not the vehicle speed Vo of the own vehicle 102 is higher than the sum Vad+Vrma of the vehicle speed Vad of the other vehicle in the lane change target and the maximum relative speed magnitude Vrma. In other words, the CPU determines whether or not the relative speed Vr (=Vo-Vad) of the own vehicle 102 with respect to the other vehicle is higher than the magnitude Vrma of the maximum relative speed. The CPU continues the current control to S 80 when a negative determination result is obtained, and continues the current control to S 70 when a positive determination result is obtained.In S 70, the CPU determines whether or not the own vehicle 102 can be decelerated. The CPU passes the current control to S 90 when a negative determination result is obtained, and passes the current control to S 80 when a positive determination result is obtained. Note that when the inter-vehicle distance between the own vehicle and the following vehicle in the same lane is equal to or less than a reference inter-vehicle distance for the determination of the deceleration, it may be determined that the own vehicle cannot be decelerated. In this case, the reference inter-vehicle distance for deceleration determination may be a positive constant, while the reference inter-vehicle distance for deceleration determination may be variably set to be larger as the relative vehicle speed of the following vehicle with respect to the own vehicle is higher.In S 80, the CPU outputs a command signal to the travel control device 90 such that the relative speed Vr of the own vehicle 102 with respect to the other vehicle becomes the lane change target -Vrma. In addition, the CPU searches for a space having a length equal to or greater than the reference length Lsre on the lane of the lane change target while controlling the vehicle speed of the own vehicle.In S 90, the CPU determines a variable Vrmad of a realizable relative speed of the own vehicle with respect to the other vehicle in the lane change target based on the inter-vehicle distance between the own vehicle 102 and the following vehicle in the lane change target and the relative speed of the following vehicle in the lane change target with respect to the own vehicle. Note that the relative speed amount Vrmad is smaller than the maximum relative speed amount Vrma. Further, the CPU determines a reference length correction Lsred as a correction minimum length of the space on the lane of the lane change target necessary for the own vehicle to perform lane change based on the relative speed magnitude Vrmad. In this case, the reference length correction Lsred is determined to be larger the larger the magnitude Vrmad of the relative speed is.In S 100, the CPU outputs a command signal to the travel control device 90 such that the relative speed Vr of the own vehicle 102 with respect to the other vehicle becomes the lane change target -Vrmad. In addition, the CPU searches for a space having a length equal to or greater than the reference length correction Lsred on the lane of the lane change target while controlling the vehicle speed of the own vehicle.In S 110, the CPU determines whether or not the vehicle speed Vo of the own vehicle 102 is less than a difference Vad-Vrma between the vehicle speed Vad of the other vehicle in the lane change target and the maximum relative speed magnitude Vrma. In other words, the CPU determines whether or not the relative speed Vr (=Vo - Vad) of the own vehicle 102 with respect to the other vehicle is lower than a sign-inverted value - Vrma of the magnitude Vrma of the maximum relative speed. The CPU continues the current control to S 130 when a negative determination result is obtained, and continues the current control to S 120 when a positive determination result is obtained.In S 120, the CPU determines whether or not the own vehicle 102 can be accelerated. The CPU proceeds the current control to S 140 when a negative determination result is present, and proceeds the current control to S 130 when a positive determination result is present. Note that when the inter-vehicle distance between the own vehicle and the preceding vehicle in the same lane is equal to or less than a reference inter-vehicle distance for the acceleration determination, it may be determined that the own vehicle cannot be accelerated. In this case, the reference inter-vehicle distance for acceleration determination may be a positive constant, while the reference inter-vehicle distance for acceleration determination may be variably set to be smaller the higher the relative speed of the preceding vehicle to the own vehicle.In S 130, the CPU outputs a command signal to the travel control device 90 so that the relative speed Vr of the own vehicle 102 with respect to the other vehicle becomes in the lane change target Vrma. In addition, the CPU searches for a space having a length equal to or greater than the reference length Lsre on the lane of the lane change target while controlling the vehicle speed of the own vehicle.In S 140, the CPU determines a variable Vrmaa of the realizable relative speed of the own vehicle with respect to the other vehicle in the lane change target based on the inter-vehicle distance between the own vehicle 102 and the preceding vehicle in the lane change target and the relative speed of the preceding vehicle in the lane change target with respect to the own vehicle. Note that the relative speed magnitude Vrmaa is less than the maximum relative speed magnitude Vrma. Further, the CPU determines the reference length correction Lsrea as the correction minimum length of a space on the lane of the lane change target necessary for the own vehicle to perform lane change based on the relative speed magnitude Vrmaa. In this case, the reference length correction Lsrea is determined to be larger the larger the magnitude Vrmaa of the relative speed is.In S 150, the CPU outputs a command signal to the travel control device 90 such that the relative speed Vr of the own vehicle 102 with respect to the other vehicle in the lane change destination becomes Vrmaa. In addition, the CPU searches for a space having a length equal to or greater than the reference length correction Lsrea on the lane of the lane change target while controlling the vehicle speed of the own vehicle.In S 160, the CPU determines whether or not there is a space that satisfies the conditions of the respective lengths as a result of the search in S 80, S 100, S 130, or S 150. If the determination result is negative, the CPU proceeds to S 180, and if the determination result is positive, the current control proceeds to S 170.In S 170, the CPU executes the lane change of the own vehicle to the lane of the lane change target by outputting the command signal to the driving control device 90 so that the own vehicle 102 moves into the space satisfying the conditions of the lengths by autonomous driving. Note that the lane change can be performed by autonomous driving in any manner well known in the art.In S 180, the CPU determines whether or not a time period equal to or longer than a reference time Δt (positive constant) has elapsed since the start of the current control. The CPU once terminates the current control and returns the current control to S 10 when a negative determination result is obtained. The CPU ends the current control without performing lane change of the own vehicle, outputs the command signal to the meter ECU 50, and displays the end of the current control on the display 52 when there is a positive determination result.As is apparent from the above description, according to the embodiment, the reference length Lsre as the minimum length of the in-lane space of the lane change target required for the own vehicle to perform lane change is calculated to be larger the higher the vehicle speed Vad of the other vehicle in the lane change target is (S 10). The length Ls of the space on the lane of the lane change target is estimated in a region where the own vehicle 102 is likely to make a lane change. Whether or not a lane change is possible is determined without searching for a gap by determining whether or not the length Ls of the gap is equal to or greater than the reference length Lsre (S 20).When the length Ls of the space is smaller than the reference length Lsre, the own vehicle allowable acceleration or deceleration amount Gxma, i.e., a maximum value of the own vehicle allowable front-rear acceleration or deceleration amount, is set based on the own vehicle traveling state (S 30). Further, the maximum relative speed amount Vrma in the search for the lane change target space is calculated from the map shown in FIG. 4 based on the allowable acceleration or deceleration amount Gxma (S 40).Further, in accelerating or decelerating the own vehicle, a space having a length equal to or greater than the minimum length is searched on the lane of the lane change target by controlling the travel control device 90 so that the relative speed of the own vehicle with respect to the other vehicle becomes a target relative speed (S 80, S 130).The allowable acceleration or deceleration amount Gxma is set to a value that is larger the smaller the distance Ld from the current location of the own vehicle 102 to the branch point Pbp is. The allowable acceleration or deceleration amount Gxma is set to a value larger when the driving mode is the sport mode than when the driving mode is the comfort mode. Further, the allowable acceleration or deceleration amount Gxma is set to a value larger when the lane change request is a driver's request (operation of the selector lever) than when the lane change request is a navigation device 80 request (vehicle driving control request).Thus, the own vehicle speed Vo can be controlled so that the relative speed Vr (=Vo-Vad) of the own vehicle with respect to the other vehicle traveling on the lane of the lane change target becomes the target relative speed Vrma calculated depending on the traveling state of the own vehicle such as the distance Ld from the current location of the own vehicle to the branch point. It is therefore possible to preferentially search for a space on the lane of the lane change target necessary for the own vehicle to make a lane change, compared to a case where the space is searched by accelerating or decelerating the own vehicle only according to the speed of the other vehicle regardless of the traveling state of the own vehicle.Specifically, when the vehicle speed Vo of the own vehicle 102 is higher than the vehicle speed Vad of the other vehicle in the lane change target (S 50) and the vehicle speed of the own vehicle is equal to or lower than a sum (Vad+ Vra) of the vehicle speed of the other vehicle and the target relative speed (S 60), a space having a length equal to or greater than the minimum length Lsre on the lane of the lane change target is searched while the vehicle speed of the own vehicle is controlled by controlling the travel control device 90 so that the relative speed of the own vehicle with respect to the other vehicle becomes the target relative speed (S 80). Thus, it is possible to search for a space whose length is equal to or greater than the minimum length, and thereby control the vehicle speed of the own vehicle so that the relative speed becomes the target relative speed.On the other hand, when the vehicle speed Vo of the own vehicle 102 is higher than the vehicle speed Vad of the other vehicle (S 50), the vehicle speed of the own vehicle is higher than a sum of the vehicle speed of the other vehicle and the target relative speed (S 60), and the own vehicle cannot be decelerated (S 70), the realizable relative speed Vrmad of the own vehicle with respect to the other vehicle is determined (S 90). Further, the correction minimum length Lsred of the space in which the own vehicle can make a lane change is determined based on the realizable relative speed (S 90). Further, the space having a length equal to or greater than the correction minimum length Lsred is searched on the lane of the lane change target, while the vehicle speed of the own vehicle is controlled by control of the travel control device such that the relative speed of the own vehicle with respect to the other vehicle becomes the target realizable relative speed (-Vrmad). Thus, it is possible to search for a space whose length is equal to or greater than the correction minimum length while controlling the vehicle speed of the own vehicle so that the relative speed becomes the target realizable relative speed.When the vehicle speed Vo of the own vehicle 102 is equal to or lower than the vehicle speed Vad of the other vehicle (S 50) and the vehicle speed of the own vehicle is equal to or higher than a difference (Vad-Vrma) between the vehicle speed of the other vehicle and the target relative speed (S 110), a space having a length equal to or greater than the minimum length Lsre is searched on the lane of the lane change target, while the vehicle speed of the own vehicle is controlled by controlling the travel control device 90 so that the relative speed of the own vehicle with respect to the other vehicle becomes the target relative speed (S 130). Thus, it is possible to search for a space whose length is equal to or greater than the minimum length, and thereby control the vehicle speed of the own vehicle so that the relative speed becomes the target relative speed.On the other hand, when the vehicle speed of the own vehicle is less than a difference (Vad-Vrma) between the vehicle speed of the other vehicle and the target relative speed (S 110), and the own vehicle cannot be accelerated (S 120) while the vehicle speed Vo of the own vehicle 102 is equal to or less than the vehicle speed Vad of the other vehicle (S 50), the realizable relative speed Vrmaa of the own vehicle with respect to the other vehicle is acquired (S 140). When the vehicle speed of the own vehicle is lower than a difference (Vad-Vrma) between the vehicle speed of the other vehicle and the target relative speed (S 110), and the own vehicle cannot be accelerated (S 120) while the vehicle speed Vo of the own vehicle 102 is equal to or lower than the vehicle speed Vad of the other vehicle (S 50), the correction minimum length Lsrea of the space in which the own vehicle can make a lane change is determined based on the realizable relative speed (S 140). Further, a space having a length equal to or greater than the correction minimum length Lsrea is searched on the lane of the lane change target, while the vehicle speed of the own vehicle is controlled by control of the travel control device such that the relative speed of the own vehicle with respect to the other vehicle becomes the target realizable relative speed Vrmaa (S 150). Thus, it is possible to search for a space whose length is equal to or greater than the correction minimum length while controlling the vehicle speed of the own vehicle so that the relative speed becomes the target realizable relative speed.Although the present invention has been described above in detail with respect to a specific embodiment, it should be apparent to those skilled in the art that the present invention is not limited to the above-described embodiment and other various embodiments are possible within the scope of the present invention.In the above-described embodiment, for example, in S 10, the reference length Lsre is calculated to be larger as the vehicle speed Vad of the other vehicle in the lane change target is higher. However, the reference length Lsre may be a fixed value.Further, in the above-described embodiment, in S 30, the amount Gxma of the allowable acceleration or deceleration of the own vehicle is set based on the traveling state of the own vehicle. The own vehicle traveling state includes the distance Ld from the current position of the own vehicle 102 to the branch point, the own vehicle traveling mode, and the type of the lane change request. However, any one of the distances Ld, the traveling mode of the own vehicle, and the type of the lane change request may be omitted.Further, in the above-described embodiment, it is determined in S 70 and S 120 whether or not the own vehicle 102 can be decelerated and accelerated. However, these steps may be omitted.References included in the specificationThis list of documents cited by the applicant has been produced in an automated manner and is only included for the better information of the reader. The list is not part of the German patent application or utility model application. The DPMA does not take any adhesion for any faults or omissions.Patent Literature citedJP 2021-149 119 A [0003, 0004]
Claims
A lane change assist device comprising: an object target information acquisition device that acquires information on an object target in the vicinity of an own vehicle; and a control unit configured to estimate a vehicle speed of another vehicle traveling on a lane of a lane change target on the basis of the information acquired by the object target information acquisition device, determine a minimum length of a space on the lane of the lane change target necessary for the own vehicle to perform lane change on the basis of the estimated vehicle speed of the other vehicle, and estimate an actual length of a space on the lane of the lane change target on the basis of the information acquired by the object target information acquisition device, and perform possibility determination that determines on the basis of the minimum length and the actual length, whether the lane change of the own vehicle to the lane change target is possible, wherein the control unit is configured to, when the possibility determination is impossible, set an allowable acceleration or deceleration of the own vehicle based on a traveling state of the own vehicle, calculate a target relative speed of the own vehicle with respect to the other vehicle based on the allowable acceleration or deceleration, and search for a space on the lane of the lane change target required for the own vehicle to perform a lane change while controlling a vehicle speed of the own vehicle in such a manner that a relative speed of the own vehicle with respect to the other vehicle becomes the target relative speed.The lane change assist device according to claim 1, wherein the control unit is configured to, when the vehicle speed of the own vehicle is higher than the vehicle speed of the other vehicle and the vehicle speed of the own vehicle is equal to or lower than a sum of the vehicle speed of the other vehicle and the target relative speed, search for a space equal to or greater than the minimum length on the lane of the lane change target while controlling the vehicle speed of the own vehicle in such a manner that the relative speed of the own vehicle with respect to the other vehicle becomes the target relative speed.The lane change assist device according to claim 1, wherein the control unit is configured to, when the vehicle speed of the own vehicle is higher than the vehicle speed of the other vehicle and the vehicle speed of the own vehicle is higher than a sum of the vehicle speed of the other vehicle and the target relative speed, determine a realizable relative speed of the own vehicle with respect to the other vehicle, determine a minimum correction length of a space in which the own vehicle can make a lane change based on the realizable relative speed, and search for a space equal to or greater than the minimum correction length on the lane of the lane change target while controlling the vehicle speed of the own vehicle such that the relative speed of the own vehicle with respect to the other vehicle becomes the realizable relative speed.The lane change assist device according to claim 1, wherein the control unit is configured to, when the vehicle speed of the own vehicle is equal to or lower than the vehicle speed of the other vehicle and the vehicle speed of the own vehicle is equal to or higher than a difference between the vehicle speed of the other vehicle and the target relative speed, search for a space equal to or greater than the minimum length on the lane of the lane change target while controlling the vehicle speed of the own vehicle such that the relative speed of the own vehicle with respect to the other vehicle becomes the target relative speed.The lane change assist device according to claim 1, wherein the control unit is configured to, when the vehicle speed of the own vehicle is equal to or lower than the vehicle speed of the other vehicle and the vehicle speed of the own vehicle is lower than a difference between the vehicle speed of the other vehicle and the target relative speed, determine a realizable relative speed of the own vehicle with respect to the other vehicle, determine a correction minimum length of a space in which the own vehicle can make a lane change based on the realizable relative speed, and search a space equal to or greater than the correction minimum length on the lane of the lane change target while controlling the vehicle speed of the own vehicle in such a manner that the relative speed of the own vehicle with respect to the other vehicle becomes the realizable relative speed.