Lane change assist system

Abstract

To provide a lane change support device capable of preferably exploring a space of a target lane for change by controlling speed of one's own vehicle depending on traveling conditions of the vehicle, such as the urgency of lane change.SOLUTION: Provided is a lane change support device configured to estimate a speed Vad of another vehicle traveling in a target lane for change, determine a minimum length of a space that is needed for the target lane for change on the basis of the other vehicle's speed, estimate an actual length of the space of the target lane for change, and determine whether or not to change to the target lane on the basis of the minimum length and the actual length. When it is determined that the lane change is not possible, a target relative speed of the own vehicle to the other vehicle is calculated based on an allowable acceleration / deceleration for the own vehicle set on the basis of the traveling state of the own vehicle, and while the speed of the own vehicle is controlled so as for the relative speed to be a target relative speed, the space that is needed for the target lane for change is explored.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a lane change support device for vehicles such as automobiles.

Background Art

[0002] As one of the lane change support devices, there is known a lane change support device that determines whether or not a lane change of the host vehicle is possible, and when the lane change of the host vehicle is not possible, controls the vehicle speed of the host vehicle to search for whether there is a space for lane change in the lane of the lane change destination.

[0003] For example, in Patent Document 1 below, it is determined whether or not a lane change of the host vehicle is approved. When the lane change is not approved, the host vehicle is accelerated or decelerated according to the speed of other vehicles traveling in the lane of the lane change destination, and a lane change support device that determines whether or not the lane change of the host vehicle is possible is described. According to this type of lane change support device, it is possible to efficiently determine whether or not a lane change is possible as compared with the case where the host vehicle is not accelerated or decelerated.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

[0005] 〔Problems to be Solved by the Invention〕 However, in a conventional lane change support device such as the device described in Patent Document 1 above, the host vehicle is accelerated or decelerated only according to the speed of other vehicles traveling in the lane of the lane change destination without considering the urgency of the lane change or the like. Therefore, it is not possible to preferably search for a space for lane change while controlling the speed of the host vehicle according to the traveling situation of the host vehicle such as the urgency of the lane change.

[0006] The present invention provides an improved lane change assistance device that can favorably search for a space for changing lanes by controlling the speed of the vehicle according to the vehicle's driving conditions, such as the urgency of the lane change. [Means for solving the problem and the effects of the invention]

[0007] According to the present invention, a lane change support device (100) is provided, which includes a target information acquisition device (18) that acquires information about targets around the vehicle (102), and a control unit (driving support ECU 10) configured to estimate the vehicle speed (Vad) of other vehicles (112, 114) traveling in the lane to be changed to (110) based on the information acquired by the target information acquisition device, determine the minimum length (Lsre) of the space in the lane to be changed to that is necessary for the vehicle to change lanes based on the estimated vehicle speed of the other vehicles (S10), estimate the actual length (Ls) of the space in the lane to be changed to that is necessary based on the information acquired by the target information acquisition device, and determine whether the vehicle can change lanes to the lane to be changed to that lane based on the minimum length and the actual length (S20).

[0008] The control unit (driving support ECU 10) is configured to, when it is not possible to determine whether it is possible or not (S20), set the vehicle's allowable acceleration / deceleration speed (Gxma) based on the vehicle's driving conditions (S30), calculate the target relative speed (Vrma) of the vehicle relative to other vehicles based on the allowable acceleration / deceleration speed (S40), and while controlling the vehicle speed of the vehicle so that the relative speed of the vehicle relative to other vehicles becomes the target relative speed, search for space in the lane to which the vehicle will change lanes (S80, S100, S130, S150).

[0009] According to the above configuration, if the feasibility determination is not possible, the vehicle's allowable acceleration and deceleration speed is set based on the vehicle's driving conditions, and the target relative speed of the vehicle relative to other vehicles is calculated based on the allowable acceleration and deceleration speed. Furthermore, while controlling the vehicle's speed so that its relative speed relative to other vehicles becomes the target relative speed, the system searches for space in the lane to which the vehicle will change lanes.

[0010] Therefore, the vehicle's speed can be controlled so that the relative speed of the vehicle with respect to other vehicles traveling in the lane it is changing into becomes a target relative speed calculated according to the vehicle's driving conditions. Consequently, compared to the case where the vehicle accelerates and decelerates and searches for space based solely on the speed of other vehicles, the vehicle can more effectively search for space in the lane it is changing into that is necessary for the vehicle to change lanes. [Aspects of the Invention]

[0011] In one embodiment of the present invention, the control unit (driving support ECU 10) is configured to control the vehicle speed of its own vehicle so that the relative speed of its own vehicle with respect to the other vehicle becomes the target relative speed (Vad + Vrma) when the vehicle speed of its own vehicle (Vo) is greater than the vehicle speed of the other vehicle (Vad) (S50) and the vehicle speed of its own vehicle is less than or equal to the sum of the vehicle speed of the other vehicle and the target relative speed (Vad + Vrma) (S60), while searching for a space of a minimum length or greater in the lane to which it will change lanes (S80).

[0012] In another embodiment of the present invention, the control unit (driving support ECU 10) is configured to determine the achievable relative speed of the vehicle with respect to the other vehicle (Vrmaa) when the vehicle speed of the vehicle is greater than the vehicle speed of the other vehicle (S50) and the vehicle speed of the vehicle is greater than the sum of the vehicle speed of the other vehicle and the target relative speed (Vad + Vrma) (S60), determine the minimum corrected length (Lsrea) of the space in which the vehicle can change lanes based on the achievable relative speed (S90), and search for a space in the lane to which the vehicle will change lanes that is greater than or equal to the minimum corrected length (S100) while controlling the vehicle speed of the vehicle so that the relative speed of the vehicle with respect to the other vehicle becomes the achievable target relative speed (-Vrmaa).

[0013] Furthermore, in another embodiment of the present invention, the control unit (driving support ECU 10) is configured to control the vehicle speed of its own vehicle so that the relative speed of its own vehicle relative to the other vehicle becomes the target relative speed (Vad-Vrma) when the vehicle speed of its own vehicle is less than or equal to the vehicle speed of the other vehicle (S50) and the vehicle speed of its own vehicle is greater than or equal to the difference (Vad-Vrma) between the vehicle speed of the other vehicle and the target relative speed (S110), while searching for a space of a minimum length or greater in the lane to which the vehicle will change lanes (S130).

[0014] Furthermore, in another embodiment of the present invention, the control unit (driving support ECU 10) is configured to determine the achievable relative speed of the vehicle with respect to the other vehicle (Vrmaa) when the vehicle speed of the vehicle is less than or equal to the vehicle speed of the other vehicle (S50) and the vehicle speed of the vehicle is less than the difference between the vehicle speed of the other vehicle and the target relative speed (Vad-Vrma) (S110), determine the minimum corrected length (Lsrea) of the space in which the vehicle can change lanes based on the achievable relative speed (S140), and search for a space in the lane to which the vehicle will change lanes that is greater than or equal to the minimum corrected length (S150) while controlling the vehicle speed of the vehicle so that the relative speed of the vehicle with respect to the other vehicle becomes the achievable target relative speed (Vrmaa).

[0015] In the above description, other objects, other features, and incidental advantages of the present invention will be readily apparent from the description of embodiments of the present invention, which will be described with reference to the following drawings. [Brief explanation of the drawing]

[0016] [Figure 1] This is a schematic diagram showing a lane change assistance device according to an embodiment. [Figure 2] This is a flowchart corresponding to the lane change assistance control program in the embodiment. [Figure 3] This diagram shows a map used to calculate the reference length Lsre, which is the minimum length of space in the lane your vehicle needs to change into for you to change lanes, based on the vehicle speed Vad of the other vehicle in the lane you are changing into. [Figure 4]FIG. is a diagram showing a map for calculating the maximum relative speed magnitude Vrma when searching for a space in the lane change destination based on the allowable acceleration magnitude Gxma. [Figure 5] FIG. is a diagram showing a situation where the host vehicle changes lanes between a preceding vehicle and a following vehicle when the preceding vehicle traveling in the lane of the lane change destination is slower than the host vehicle. [Figure 6] FIG. is a diagram showing a situation where the host vehicle changes lanes between a preceding vehicle and a following vehicle when the following vehicle traveling in the lane of the lane change destination is faster than the host vehicle.

BEST MODE FOR CARRYING OUT THE INVENTION

[0017] The lane change support device according to an embodiment of the present invention will be described in detail below with reference to the attached drawings.

[0018] As shown in FIG. 1, the lane change support device 100 according to an embodiment of the present invention is applied to a vehicle 102 and includes a driving support ECU 10. The vehicle 102 is a vehicle capable of autonomous driving and includes a drive ECU 20, a brake ECU 30, an electric power steering ECU 40, and a meter ECU 50. An ECU means an electronic control unit (Electronic Control Unit) having a microcomputer as a main part. In the following description, electric power steering is referred to as EPS.

[0019] The microcomputer of each ECU includes a CPU, a ROM, a RAM, a readable and writable non-volatile memory (N / M), an interface (I / F), and the like. The CPU realizes various functions by executing instructions (programs, routines) stored in the ROM. Further, these ECUs are connected to each other via a CAN (Controller Area Network) 104 so that data can be exchanged (communicated). Therefore, the detection value of a sensor (including a switch) connected to a specific ECU is also transmitted to other ECUs.

[0020] The driving support ECU 10 is a central control device that performs driving support controls such as lane change support control and lane keeping control. In the embodiment, as will be described in detail later, the driving support ECU 10 cooperates with other ECUs to execute the lane change support control of the vehicle 102.

[0021] A camera sensor 12, a radar sensor 14, and a setting operator 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 a target information acquisition device 18 that acquires target information around the vehicle 102.

[0022] Although not shown in the figure, each camera device of the camera sensor 12 includes a camera unit that photographs the surroundings of the vehicle 102, and a recognition unit that analyzes the image data obtained by the camera unit to recognize targets such as white lines on the road and other vehicles. The recognition unit supplies information regarding the recognized targets to the driving support ECU 10 at predetermined time intervals.

[0023] Each radar device of the radar sensor 14 includes a radar transceiver and a signal processing unit (not shown). The radar transceiver emits radio waves in the millimeter wave band (hereinafter referred to as "millimeter waves"), and receives the millimeter waves (i.e., reflected waves) reflected by solid objects (e.g., other vehicles, bicycles, etc.) existing within the radiation range. The signal processing unit is based on the phase difference between the transmitted millimeter wave and the received reflected wave, the attenuation level of the reflected wave, and the time from transmitting the millimeter wave to receiving the reflected wave, etc., and supplies information representing the distance between the host vehicle and the solid object, the relative speed between the host vehicle and the solid object, and the relative position (direction) of the solid object with respect to the host vehicle to the driving support ECU 10 at predetermined time intervals. Note that, instead of or in addition to the radar sensor 14, LiDAR (Light Detection And Ranging) may be used.

[0024] The setting control unit 16 is located in a position that can be operated by the driver, similar to a steering wheel (not shown in Figure 1), and is operated by the driver. Although not shown in Figure 1, the setting control unit 16 includes a lane change assist switch. The driver assistance ECU 10 starts lane change assist control when the lane change assist switch is ON and the predetermined conditions described later are met, as will be explained in detail later.

[0025] The drive ECU 20 is connected to a drive unit 22 that accelerates the vehicle 102 by applying driving force to the drive wheels 24. Normally, the drive ECU 20 controls the drive unit 22 so that the driving force generated by the drive unit 22 changes in accordance with the driver's driving operation, and when it receives a command signal from the driver assistance ECU 10, it controls the drive unit 22 based on the command signal.

[0026] The braking ECU 30 is connected to a braking device 32 that decelerates the vehicle 102 by applying braking force to the wheels 34. Normally, the braking ECU 30 controls the braking device 32 so that the braking force generated by the braking device 32 changes in accordance with the driver's braking operation. When it receives a command signal from the driver assistance ECU 10, it performs automatic braking by controlling the braking device 32 based on the command signal. When braking force is applied to the wheels, brake lights (not shown in Figure 1) are illuminated.

[0027] The EPS / ECU 40 is connected to the EPS device 42. Based on the steering torque Ts and vehicle speed Vo detected by the driving operation sensor 60 and vehicle condition sensor 70 (described later), the EPS / ECU 40 controls the steering assist torque by controlling the EPS device 42 in a manner known in the art, thereby reducing the driver's steering burden. Furthermore, by controlling the EPS device 42, the EPS / ECU 40 can steer the steering wheels 44 as needed. Therefore, the EPS / ECU 40 and the EPS device 42 function as an automatic steering system that automatically steers the steering wheels as needed.

[0028] As can be seen from the above explanation, the drive ECU 20, drive unit 22, brake ECU 30, brake unit 32, EPS ECU 40, and EPS unit 42 function as a driving control device 90 that controls the driving of the vehicle 102, including braking, driving, turning, etc.

[0029] A touch-panel display unit 52 is connected to the meter ECU 50 to display the status of control by the driver assistance ECU 10. The display unit 52 may be, for example, a multi-information display that displays meters and various other information, or it may be the display of the navigation device 80 described later. As described later, when the display unit 52 receives a signal from the driver assistance ECU 10, it displays the status of lane change support control.

[0030] The driving operation sensor 60 and the vehicle condition sensor 70 are connected to CAN 104. Information detected by the driving operation sensor 60 and the vehicle condition sensor 70 (referred to as sensor information) is transmitted to CAN 104. The sensor information transmitted to CAN 104 can be used as appropriate by each ECU. Note that the sensor information may be information from a sensor connected to a specific ECU and transmitted to CAN 104 from that specific ECU.

[0031] The driving operation sensor 60 includes a drive operation amount sensor for detecting the amount of operation of the accelerator pedal, and a braking operation amount sensor for detecting master cylinder pressure or the force applied to the brake pedal. The driving operation sensor 60 also includes a steering angle sensor for detecting the steering angle θ and a steering torque sensor for detecting the steering torque Ts. Furthermore, the driving operation sensor 60 includes a turn lever operated when the driver wishes to change lanes, and a mode switch for switching the driving mode of the vehicle 102 between sport mode and comfort mode. Sport mode is a mode that prioritizes the vehicle's handling responsiveness over ride comfort, while comfort mode is a mode that prioritizes ride comfort over vehicle handling responsiveness.

[0032] The vehicle condition 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 of the vehicle in the longitudinal direction, a lateral acceleration sensor for detecting the acceleration of the vehicle in the lateral direction, and a yaw rate sensor for detecting the yaw rate of the vehicle.

[0033] 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 map information and road information from an external source. The navigation device 80 functions as a device for acquiring information on the current location of the vehicle 102 and outputs a signal to the driver assistance ECU 10 indicating the vehicle's current location on the map. Furthermore, when a destination is entered, the navigation device 80 determines a target route from the vehicle 102's current location to the destination and guides the vehicle to travel along the target route. In particular, when there is a fork in the road ahead of the vehicle and the vehicle needs to change lanes before the fork in the road in order to travel along the target route, the navigation device 80 displays the need for a lane change on the display 52 to notify the driver and also notifies the driver assistance ECU 10.

[0034] In this embodiment, the ROM of the driver assistance ECU 10 stores a lane change assistance control program corresponding to the flowchart shown in Figure 2. The CPU of the driver assistance ECU 10 performs lane change assistance by executing lane change assistance control according to this program. <Lane change support control (Figure 2)>

[0035] Next, the lane change support control program in the embodiment will be described with reference to the flowchart shown in Figure 2. The lane change support control according to the flowchart shown in Figure 2 is started by the CPU of the driver support ECU 10 when the turn lever is operated or when a signal indicating that a lane change is necessary is input from the navigation device 80, while the lane change support switch is ON, and is executed repeatedly at predetermined intervals.

[0036] First, in step 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, as acquired by the target information acquisition device 18, and the speed Vo of the own vehicle. Furthermore, based on the speed Vad of the other vehicle, the CPU calculates a reference length Lsre from the map shown in Figure 3 as the minimum length of space in the lane at the lane change destination that is necessary for the own vehicle to change lanes. As shown in Figure 3, the reference length Lsre is calculated to increase as the speed Vad of the other vehicle increases.

[0037] For example, Figures 5 and 6 show the situations in which the vehicle changes lanes between the preceding vehicle 112 and the following vehicle 114, which are traveling in the lane 110 to which the vehicle is changing lanes, when the preceding vehicle 112 and the following vehicle 114 are traveling in the lane to which the vehicle is changing lanes, respectively, when the preceding vehicle 112 is slower and the following vehicle is faster. Specifically, (A) shows the situation before the lane change, and (B) shows the situation after the lane change.

[0038] If there is ample space in the lane to which the vehicle is changing lanes, searching for space is unnecessary. However, if the space in the lane to which the vehicle is changing lanes is small, searching for space is necessary, and the vehicle should be changed lanes in such a way that, upon completion of the lane change, a minimum following distance Lmin is maintained between the vehicle 102, the preceding vehicle 110, and the following vehicle 112.

[0039] As can be seen from (B), if the length of the vehicle 102 is Lv, then the lane change is not possible unless there is a space of 2Lmin+Lv or more in the lane to which the vehicle is changing. Therefore, the above reference length Lsre may be 2Lmin+Lv. As shown in Figure 3, the reference length Lsre is calculated to be larger as the vehicle speed Vad of other vehicles increases. Note that if there is a preceding vehicle 112 and a following vehicle 114 in the lane 110 to which the vehicle is changing, and their vehicle speeds are different, then the vehicle speed Vad may be the average value of the vehicle speeds of the two vehicles.

[0040] In step S20, the CPU estimates the length Ls of the space in the lane to which the vehicle 102 can change lanes in the area where it is possible to change lanes, based on the lane change destination information acquired by the target information acquisition device 18. Furthermore, the CPU determines whether the length Ls of the space is greater than or equal to the reference length Lsre, that is, whether it is possible to change lanes without searching for space. If the CPU makes a positive determination, it proceeds to step S170; if it makes a negative determination, it proceeds to step S30.

[0041] In step S30, the CPU sets the magnitude of the vehicle's allowable acceleration / deceleration, Gxma, based on the vehicle's driving conditions, i.e., the maximum value of the forward / reverse acceleration / deceleration allowed for the vehicle. In this embodiment, the vehicle's driving conditions are at least one of the distance Ld from the vehicle 102's current location to the junction Pbp (see Figures 5 and 6), the vehicle's driving mode, and the type of lane change request. The magnitude of the allowable acceleration / deceleration, Gxma, is set to a larger value as the distance Ld decreases, and is set to a larger value when the driving mode is sport mode compared to when the driving mode is comfort mode. Furthermore, the magnitude of the allowable acceleration / deceleration, Gxma, is set to a larger value when the lane change request is a request from the driver (operation of the turn lever) compared to when the lane change request is a request from the navigation device 80 (control request).

[0042] In step S40, the CPU calculates the maximum relative speed Vrma when searching for a space to change lanes, based on the magnitude of the allowable acceleration / deceleration Gxma, from the map shown in Figure 4. The maximum relative speed Vrma is the maximum value of the relative speed Vr (=Vo-Vad) of the vehicle 102 with respect to other vehicles at the lane change destination.

[0043] Next, we will explain why the relationship between the magnitude of the allowable acceleration / deceleration Gxma and the magnitude of the maximum relative velocity Vrma is as shown in Figure 4.

[0044] Let Gxo be the acceleration / deceleration of vehicle 102. In the situations shown in Figures 4 and 5, by decelerating and accelerating vehicle 102, the distance Lr that vehicle 102 is displaced relative to other vehicle until its speed Vo becomes the speed Vad of other vehicle is expressed by the following equation (1). Lr = Vr * Vr / (2 * Gxo) …(1)

[0045] In the situation shown in Figure 5, in order to maintain a distance of at least Lmin between vehicle 102 and the preceding vehicle 112 after the lane change, vehicle 102 must begin decelerating when the distance between vehicle 102 and the preceding vehicle 112 is Lmin-Lr or greater. Furthermore, in order to maintain a distance of at least Lmin between vehicle 102 and the following vehicle 114 after the lane change, vehicle 102 must begin decelerating when the distance between vehicle 102 and the following vehicle 114 is Lmin+Lr or greater.

[0046] Furthermore, if a vehicle initiates a lane change while it is ahead of the vehicle it is changing lanes to, the distance between the vehicle and the vehicle ahead after the lane change may become too small. Therefore, in order to set the distance between the vehicle and the vehicle ahead after the lane change to the minimum distance Lmin, the distance between the vehicle and the vehicle ahead at the start of the lane change must be greater than or equal to Lfront. Lfront is a smaller value as the relative speed Vr increases, and can be 0 when the vehicle starts moving to change lanes.

[0047] If Lmin-Lr is smaller than Lfront, the distance between your vehicle and the vehicle ahead at the start of the lane change will be Lfront. Therefore, the distance between your vehicle and the vehicle ahead after the lane change will be Lfront+Lr, which is larger than Lmin. Thus, your vehicle cannot change lanes into a space with a length of 2Lmin+Lv.

[0048] For a vehicle to change lanes into a space of length 2Lmin+Lv, Lfront must be greater than or equal to Lmin-Lr. Assuming Lfront is equal to Lmin-Lr, equation (2) below holds from equation (1) above, and the relative velocity Vr is expressed by equation (3) below. Lfront = Lmin - Lr =Lmin-Vr*Vr / (2*Gxo) …(2) Vr = {(Lmin - Lfront) * 2 * Gxo} 1 / 2 …(3)

[0049] In the situation shown in Figure 6, in order to maintain a distance of at least Lmin between vehicle 102 and the preceding vehicle 112 after a lane change, vehicle 102 must begin accelerating when the distance between vehicle 102 and the preceding vehicle 112 is at least Lmin + Lr. Also, in order to maintain a distance of at least Lmin between vehicle 102 and the following vehicle 114 after a lane change, vehicle 102 must begin accelerating when the distance between vehicle 102 and the following vehicle 114 is at least Lmin - Lr.

[0050] Furthermore, if a vehicle starts a lane change while it is traveling behind the vehicle it is changing lanes to, the distance between the vehicle and the vehicle after the lane change may become too small. Therefore, in order to set the distance between the vehicle and the vehicle after the lane change to the minimum distance Lmin, the distance between the vehicle and the vehicle at the start of the lane change must be Lrear or greater. Lrear is a smaller value as the relative speed Vr increases, and can be 0 when the vehicle starts moving to change lanes.

[0051] If Lmin-Lr is less than Lrear, the distance between your vehicle and the following vehicle at the start of the lane change will be Lrear+Lr, which is greater than Lmin. Therefore, your vehicle cannot change lanes into a space of length 2Lmin+Lv.

[0052] For a vehicle to change lanes into a space of length 2Lmin+Lv, Lrear must be greater than or equal to Lmin-Lr. Assuming Lrear is equal to Lmin-Lr, equation (4) below holds from equation (1) above, and the relative velocity Vr is expressed by equation (5) below. Lrear = Lmin - Lr =Lmin-Vr*Vr / (2*Gxo) …(4) Vr = {(Lmin - Lrear) * 2 * Gxo} 1 / 2 …(5)

[0053] Considering that Lfront and Lrear must be 0 in equations (3) and (5) above, and that Lfront and Lrear must be greater than or equal to Lmin-Lr, the following equation (6) holds. Therefore, the relationship between the magnitude of the allowable acceleration / deceleration Gxma and the magnitude of the maximum relative velocity Vrma is as shown in Figure 4. Vr = (Lmin * 2 * Gxo) 1 / 2 …(6)

[0054] In step S50, the CPU determines whether the speed Vo of its own vehicle 102 is greater than the speed Vad of the other vehicle it is changing lanes into, that is, whether its own vehicle is faster than the other vehicle it is changing lanes into. If the CPU determines that it is not, it proceeds to step S110; if it determines that it is, it proceeds to step S60.

[0055] In step S60, the CPU determines whether the vehicle speed Vo of the vehicle 102 is greater than the sum of the vehicle speed Vad of the other vehicle to which the vehicle is changing lanes and the magnitude of the maximum relative speed Vrma, Vad+Vrma. That is, the CPU determines whether the relative speed Vr (=Vo-Vad) of the vehicle 102 with respect to the other vehicle is greater than the magnitude of the maximum relative speed Vrma. If the CPU determines that it is not true, it proceeds to step S80; if it determines that it is true, it proceeds to step S70.

[0056] In step S70, the CPU determines whether or not it is possible to decelerate its own vehicle 102. If the CPU determines that it is not possible, it proceeds to step S90; if it determines that it is possible, it proceeds to step S80. Note that if the distance between the own vehicle and the following vehicle in the same lane is less than or equal to the reference distance for deceleration determination, it may be determined that the own vehicle cannot be decelerated. In this case, the reference distance for deceleration determination may be a positive constant, but it may be set to be variable so that it becomes larger as the relative speed of the following vehicle to the own vehicle increases.

[0057] In step S80, the CPU outputs a command signal to the driving control device 90 so that the relative speed Vr of the vehicle 102 with respect to the other vehicle in the lane it is changing to becomes -Vrma, and while controlling the speed of the vehicle, it searches for a space in the lane it is changing to that is at least the reference length Lsre.

[0058] In step S90, the CPU determines the magnitude of the achievable relative speed Vrmad of the vehicle 102 with respect to the other vehicle at the lane change destination, based on the distance between the vehicle 102 and the following vehicle at the lane change destination and the relative speed of the following vehicle at the lane change destination with respect to the vehicle 102. Note that the magnitude of the relative speed Vrmad is smaller than the magnitude of the maximum relative speed Vrma. The CPU also determines the correction reference length Lsred, which is the minimum corrected length of space in the lane change destination required for the vehicle to change lanes, based on the magnitude of the relative speed Vrmad. In this case, the correction reference length Lsred is determined to be larger as the magnitude of the relative speed Vrmad increases.

[0059] In step S100, the CPU outputs a command signal to the driving control device 90 so that the relative speed Vr of the vehicle 102 with respect to the other vehicle to which it is changing lanes becomes -Vrmad, and while controlling the speed of the vehicle, it searches for a space in the lane to which it is changing lanes that is longer than or equal to the correction reference length Lsred.

[0060] In step S110, the CPU determines whether the vehicle speed Vo of the vehicle 102 is less than the difference Vad-Vrma between the vehicle speed Vad of the other vehicle to which the vehicle is changing lanes and the magnitude of the maximum relative speed Vrma. That is, the CPU determines whether the relative speed Vr (=Vo-Vad) of the vehicle 102 with respect to the other vehicle is less than the sign-inverted value -Vrma of the magnitude of the maximum relative speed Vrma. If the CPU determines it is negative, it proceeds to step S130; if it determines it is positive, it proceeds to step S120.

[0061] In step S120, the CPU determines whether or not the vehicle 102 can be accelerated. If the CPU determines that it cannot be accelerated, it proceeds to step S140; if it determines that it cannot be accelerated, it proceeds to step S130. Note that if the distance between the vehicle and the preceding vehicle in the same lane is less than or equal to the reference distance for acceleration determination, it may be determined that the vehicle cannot be accelerated. In this case, the reference distance for acceleration determination may be a positive constant, but it may be set to be variable so that it becomes smaller as the relative speed of the preceding vehicle to the vehicle increases.

[0062] In step S130, the CPU outputs a command signal to the driving control device 90 so that the relative speed Vr of the vehicle 102 with respect to the other vehicle to which it is changing lanes becomes Vrma, and while controlling the speed of the vehicle, it searches for a space in the lane to which it is changing lanes that is at least the reference length Lsre.

[0063] In step S140, the CPU determines the magnitude of the achievable relative speed Vrmaa of the vehicle 102 with respect to the other vehicle it is changing lanes to, based on the distance between the vehicle 102 and the preceding vehicle it is changing lanes to, and the relative speed of the preceding vehicle it is changing lanes to. Note that the magnitude of the relative speed Vrmaa is smaller than the magnitude of the maximum relative speed Vrma. The CPU also determines the correction reference length Lsrea, which is the minimum corrected length of space in the lane it is changing lanes to, required for the vehicle to change lanes, based on the magnitude of the relative speed Vrmaa. In this case, the correction reference length Lsrea is determined to be larger as the magnitude of the relative speed Vrmaa increases.

[0064] In step S150, the CPU outputs a command signal to the driving control device 90 so that the relative speed Vr of the vehicle 102 with respect to the other vehicle in the lane it is changing to becomes Vrmaa, and while controlling the speed of the vehicle, it searches for a space in the lane it is changing to that is longer than or equal to the correction reference length Lsrea.

[0065] In step S160, the CPU determines whether, as a result of the search in steps S80, S100, S130, or S150, it has determined that there is a space that satisfies the respective length requirements. If the CPU determines that there is no space, it proceeds to step S180; if it determines that there is no space, it proceeds to step S170.

[0066] In step S170, the CPU outputs a command signal to the driving control device 90 to automatically move the vehicle 102 to a space that meets the length requirements, thereby executing a lane change for the vehicle to the destination lane. Note that the lane change by automatic driving may be performed in any manner known in the art.

[0067] In step S180, the CPU determines whether a reference time Δt (a positive constant) or longer has elapsed since the start of this control. If the CPU determines that it has not, it terminates this control and returns to step S10. If it determines that it has not, it terminates this control without performing a lane change of the vehicle, outputs a command signal to the meter ECU 50, and displays the termination of this control on the display unit 52.

[0068] As can be seen from the above explanation, according to the embodiment, the reference length Lsre, which is the minimum length of space in the lane to which the vehicle will change lanes, is calculated to be larger as the vehicle speed Vad of the other vehicle at the lane to which the vehicle will change lanes increases (S10). The length Ls of the space in the lane to which the vehicle will change lanes is estimated in the area in which the vehicle 102 may be able to change lanes, and by determining whether the length Ls of the space is greater than or equal to the reference length Lsre, it is determined whether or not a lane change is possible without searching for space (S20).

[0069] When the length Ls of the space is less than the reference length Lsre, the magnitude of the vehicle's allowable acceleration and deceleration, Gxma, i.e., the maximum value of the forward and backward acceleration and deceleration allowed for the vehicle, is set based on the vehicle's driving conditions (S30). Furthermore, based on the magnitude of the allowable acceleration and deceleration, Gxma, the magnitude of the maximum relative speed Vrma when searching for a space to change lanes to is calculated from the map shown in Figure 4 (S40).

[0070] Furthermore, the vehicle accelerates and decelerates by controlling the driving control device 90 so that the relative speed of the vehicle with respect to other vehicles becomes the target relative speed, while a space of at least the minimum length in the lane to which the vehicle will change is searched (S80, S130).

[0071] The magnitude of the permissible acceleration / deceleration, Gxma, is set to a larger value the smaller the distance Ld from the vehicle 102's current location to the junction Pbp, and is set to a larger value when the driving mode is sport mode compared to when the driving mode is comfort mode. Furthermore, the magnitude of the permissible acceleration / deceleration, Gxma, is set to a larger value when the lane change request is a request from the driver (operation of the turn lever) compared to when the lane change request is a request from the navigation device 80 (request for vehicle driving control).

[0072] Therefore, the vehicle speed Vo can be controlled so that the relative speed Vr (=Vo-Vad) of the vehicle with respect to other vehicles traveling in the lane to which the vehicle is changing lanes becomes a target relative speed Vrma calculated according to the vehicle's driving conditions, such as the distance Ld from the vehicle's current location to the junction. Consequently, compared to the case where the vehicle accelerates and decelerates and searches for space only according to the speed of other vehicles, regardless of the vehicle's driving conditions, the vehicle can more effectively search for space in the lane to which it is changing lanes.

[0073] In particular, when the vehicle speed Vo of the own vehicle 102 is greater than the vehicle speed Vad of the other vehicle to which the vehicle is changing lanes (S50) and the vehicle speed of the own vehicle is less than or equal to the sum of the vehicle speed of the other vehicle and the target relative speed (Vrma + Vrma) (S60), the driving control device 90 is controlled to control the vehicle 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 a space of minimum length Lsre or greater in the lane to which the vehicle is changing lanes is searched (S80). Thus, the vehicle speed of the own vehicle can be controlled so that the relative speed becomes the target relative speed, while a space of minimum length or greater can be searched.

[0074] In contrast, if the vehicle speed Vo of the vehicle 102 is greater than the vehicle speed Vad of the other vehicle (S50), but the vehicle speed of the vehicle is greater than the sum of the vehicle speed of the other vehicle and the target relative speed (S60), and deceleration of the vehicle is impossible (S70), then the achievable relative speed Vrmad of the vehicle with respect to the other vehicle is determined (S90). Also, based on the achievable relative speed, the minimum corrected length Lsred of the space in which the vehicle can change lanes is determined (S90). Furthermore, the vehicle speed of the vehicle is controlled by controlling the driving control device so that the relative speed of the vehicle with respect to the other vehicle becomes the achievable target relative speed (-Vrmad), while a space of at least the minimum corrected length Lsred in the lane to which the vehicle will change lanes is searched. Thus, the vehicle speed of the vehicle can be controlled so that the relative speed becomes the achievable target relative speed, while a space of at least the minimum corrected length is searched.

[0075] Furthermore, when the vehicle speed Vo of the own vehicle 102 is less than or equal to the vehicle speed Vad of the other vehicle (S50) and the vehicle speed of the own vehicle is greater than or equal to the difference between the vehicle speed of the other vehicle and the target relative speed (Vad-Vrma) (S110), the driving control device 90 is controlled to control the vehicle 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 a space of minimum length Lsre or greater in the lane to which the vehicle will change lanes is searched (S130). Thus, the vehicle speed of the own vehicle can be controlled so that the relative speed becomes the target relative speed, while a space of minimum length or greater can be searched.

[0076] In contrast, if the vehicle speed Vo of the vehicle 102 is less than or equal to the vehicle speed Vad of the other vehicle (S50), but the vehicle speed of the vehicle is less than the difference between the vehicle speed of the other vehicle and the target relative speed (Vad-Vrma) (S110), and acceleration of the vehicle is impossible (S120), then the achievable relative speed Vrmaa of the vehicle with respect to the other vehicle is determined (S140). Based on the achievable relative speed, the minimum corrected length Lsrea of ​​the space in which the vehicle can change lanes is determined (S140). Furthermore, the vehicle speed of the vehicle is controlled by controlling the driving control device so that the relative speed of the vehicle with respect to the other vehicle becomes the achievable target relative speed Vrmaa, while a space of at least the minimum corrected length Lsrea in the lane to which the vehicle will change lanes is searched (S150). Thus, the vehicle speed of the vehicle can be controlled so that the relative speed becomes the achievable target relative speed, while a space of at least the minimum corrected length is searched.

[0077] Although the present invention has been described in detail above with respect to specific embodiments, it will be apparent to those skilled in the art that the present invention is not limited to the embodiments described above, and that various other embodiments are possible within the scope of the present invention.

[0078] For example, in the embodiment described above, in step S10, the reference length Lsre is calculated to be larger as the vehicle speed Vad of the other vehicle to which the lane change is made increases. However, the reference length Lsre may be a constant value.

[0079] Furthermore, in the above-described embodiment, in step S30, the magnitude of the vehicle's allowable acceleration / deceleration Gxma is set based on the vehicle's driving conditions, and the vehicle's driving conditions are the distance Ld from the vehicle 102's current location to the branching point, the vehicle's driving mode, and the type of lane change request. However, any of the distance Ld, the vehicle's driving mode, or the type of lane change request may be omitted.

[0080] Furthermore, in the above-described embodiment, steps S70 and S120 determine whether the vehicle 102 can be decelerated and accelerated, respectively. However, these steps may be omitted. [Explanation of symbols]

[0081] 10…Driver assistance ECU, 12…Camera sensor, 14…Radar sensor, 18…Target information acquisition device, 22…Drive system, 32…Braking system, 42…EPS system, 90…Driving control device, 100…Lane change support device, 102…Vehicle, 112…Preceding vehicle, 114…Following vehicle

Claims

1. A lane change support device comprising: a target information acquisition device that acquires information about targets around the vehicle; a control unit configured to estimate the speed of other vehicles traveling in the lane to which the vehicle will change based on the information acquired by the target information acquisition device, determine the minimum length of space in the lane to which the vehicle will change necessary based on the estimated speed of other vehicles, estimate the actual length of space in the lane to which the vehicle will change based on the information acquired by the target information acquisition device, and determine whether or not the vehicle can change lanes to the lane to which it will change based on the minimum length and the actual length, wherein The control unit is configured to, when the feasibility determination is not possible, set the permissible acceleration and deceleration speed of the vehicle based on the vehicle's driving conditions, calculate the target relative speed of the vehicle relative to the other vehicle based on the permissible acceleration and deceleration speed, and control the vehicle speed of the vehicle so that the relative speed of the vehicle relative to the other vehicle becomes the target relative speed, while simultaneously searching for space in the lane to which the vehicle will change lanes.

2. A lane change support device according to claim 1, wherein the control unit is configured to search for a space of the minimum length or greater in the lane to which the vehicle is to change lanes, while controlling the vehicle speed of the vehicle so that the relative speed of the vehicle with respect to the other vehicle becomes the target relative speed when the vehicle speed of the vehicle is greater than the vehicle speed of the other vehicle and the vehicle speed of the vehicle is less than or equal to the sum of the vehicle speed of the other vehicle and the target relative speed.

3. Lane change support device according to claim 1, wherein the control unit is configured to determine the achievable relative speed of the vehicle with respect to the other vehicle when the vehicle speed of the vehicle is greater than the vehicle speed of the other vehicle and the vehicle speed of the vehicle is greater than the sum of the vehicle speed of the other vehicle and the target relative speed, to determine the minimum corrected length of space in which the vehicle can change lanes based on the achievable relative speed, and to search for a space in the lane to which the vehicle will change lanes that is greater than or equal to the minimum corrected length while controlling the vehicle speed of the vehicle so that the relative speed of the vehicle with respect to the other vehicle becomes the achievable target relative speed.

4. A lane change support device according to claim 1, wherein the control unit is configured to search for a space of the minimum length or greater in the lane to which the vehicle is to change lanes, while controlling the vehicle speed of the vehicle so that the relative speed of the vehicle with respect to the other vehicle becomes the target relative speed, when the vehicle speed of the vehicle is less than or equal to the vehicle speed of the other vehicle and the vehicle speed of the vehicle is greater than or equal to the difference between the vehicle speed of the other vehicle and the target relative speed.

5. Lane change support device according to claim 1, wherein the control unit is configured to determine the achievable relative speed of the vehicle with respect to the other vehicle when the vehicle speed of the vehicle is less than or equal to the vehicle speed of the other vehicle and the vehicle speed of the vehicle is less than the difference between the vehicle speed of the other vehicle and the target relative speed, to determine the minimum corrected length of space in which the vehicle can change lanes based on the achievable relative speed, and to search for a space in the lane to which the vehicle will change lanes that is greater than or equal to the minimum corrected length while controlling the vehicle speed of the vehicle so that the relative speed of the vehicle with respect to the other vehicle becomes the achievable target relative speed.

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