Device for selecting a vehicle in front

Abstract

Ahead vehicle selection device comprising: - an object detection means (4, 41, S120) that detects an object ahead of a subject vehicle and determines a relative position and a relative velocity with respect to the subject vehicle for each ahead object; - a lateral velocity calculation means (4, 42, S150) that calculates a lateral velocity of the ahead object based on detection results of the ahead object acquired by the object detection means; - a lateral position correction means (4, 43, S160, S170) that corrects the lateral position of the ahead object with respect to a direction of travel of the subject vehicle based on the lateral velocity calculated by the lateral velocity calculation means;- a subject vehicle lane probability calculator (4, 44, S180, S190) which calculates a subject vehicle lane probability for each preceding object on the basis of the relative position of the preceding object whose lateral position has been corrected by the lateral position correction calculator, wherein the subject vehicle lane probability is a probability that the preceding object is in the same lane as the subject vehicle;and- a lead vehicle selection means (4, 45, S200) that selects a lead vehicle from the objects ahead based on the subject vehicle lane probability calculated by the subject vehicle lane probability calculation means,- wherein the lateral position correction means corrects the lateral position of the object ahead on the basis of a distance to the object ahead such that a lateral position correction amount decreases with increasing distance to the object ahead.;

Description

The present invention relates to a technology for selecting a vehicle (preceding vehicle or "preceding vehicle" for short) that travels in front of an own vehicle (subject vehicle).As a technology for reducing operating forces to be applied from a driver who drives a vehicle, a vehicle-to-vehicle control device is known. The in-vehicle control device detects a vehicle (preceding vehicle) that travels in front of the own vehicle. The in-vehicle control device controls the vehicle speed and the like to maintain a certain distance between the subject vehicle and the preceding vehicle so that the subject vehicle can automatically follow the preceding vehicle.In this type of apparatus, a radar or the like is used to detect objects (ahead objects) located in front of the subject vehicle. The preceding vehicle that should be followed by the subject vehicle is selected from the detected objects. Further, in order to enable early selection of the forward vehicle to be determined, a predicted lateral position is calculated from a lateral movement speed of the (forward) object located in front of the subject vehicle. The predicted lateral position is further used to select the forward vehicle (see, for example, JP 4 229 189 B2). The predicted sideways position information may also be regarded as position information in which the sideways position is corrected based on the sideways movement speed.The lateral position information using a radar or the like is determined based on the position at which the radar wave is reflected. Therefore, the sideways position information does not exactly indicate a specific position (such as the center of the vehicle). As a result of this effect of the sideways position information, the information about the predicted sideways position also varies. Further, an estimated path on which the subject vehicle travels has a considerable error over long distances and on curved roads. Therefore, there occurs a problem that wrong selection easily occurs when the predicted lateral position information is used to select a preceding vehicle and cancel the selection.For a better understanding of the present invention, reference is also made in the foregoing to US 2009 / 0 187 290 A1 and DE 10 2013 201 673 A1.US 2009 / 0 187 290 A1 relates to a collision prediction apparatus that accurately selects a collision target having a high probability of collision with the own vehicle, and a collision prediction method for predicting whether an own vehicle and a collision target will collide.DE 10 2013 201 673 A1 relates to a cruise control apparatus having a function that causes the own vehicle (a vehicle equipped with this vehicle control apparatus) to follow a preceding vehicle. In particular, it is the object of DE 10 2013 201 673 A1 to provide a cruise control device which enables the execution of a cruise control depending on the type of the detected front vehicle which is travelling in front of the own vehicle.It is thus an object of the present invention to provide a technology in which wrong selection is prevented in selection of a preceding vehicle using lateral position information corrected based on a lateral movement speed.This object is achieved by the features of claim 1 or claim 6. Advantageous refinements are defined in the dependent claims.A preceding vehicle selection apparatus according to the present invention includes an object detection means, a sideways movement speed calculation means, a sideways position correction means, a subject vehicle lane probability calculation means, and a preceding vehicle selection means.The object detection means detects a preceding object which is an object located in front of the subject vehicle, and determines a relative position and a relative speed with respect to each preceding object.The sideways movement speed calculation means calculates a sideways movement speed of the preceding object based on detection results of the preceding object detected by the object detection means.The sideways position correcting means corrects the sideways position of the object ahead with respect to a traveling direction of the subject vehicle on the basis of the sideways movement speed calculated by the sideways movement speed calculating means. This sideways position correcting means corrects the sideways position of the preceding object on the basis of a distance to the preceding object, so that a correction amount of the sideways position decreases as the distance to the preceding object increases.The subject vehicle lane probability calculation means calculates a subject vehicle lane probability for each preceding object based on the relative position of the preceding object whose lateral position has been corrected by the lateral position correction means. The subject vehicle lane probability is a probability that the object ahead is in the same lane as the subject vehicle.The preceding vehicle selection means selects a preceding vehicle from the preceding objects on the basis of the subject vehicle lane probability calculated by the subject vehicle lane probability calculation means.In the preceding vehicle selection apparatus of the present invention configured as described above, the subject vehicle lane probability is calculated and the preceding vehicle is selected using the sideways position corrected using the sideways movement speed. In other words, a predicted lateral position is used after a lapse of a certain period of time. Therefore, a vehicle cutting into or leaving the lane of the subject vehicle can be determined early. Accordingly, selection of a preceding vehicle can be made earlier.Further, the correction amount of the lateral position decreases as the distance increases. Therefore, wrong determination at distant distances where errors increase can be prevented, while early determination at near distances is ensured.Numbers in brackets recited in the claims show the correlations with certain embodiments described below as an aspect of the invention. However, the technical scope of the present invention is not limited thereby.Further, the present invention can be realized by various embodiments in addition to the preceding vehicle selection apparatus described above. For example, the present invention can be realized by a system of which the preceding vehicle selection device is a component or a program that allows a computer to function as any means that is part of the preceding vehicle selection device.In the accompanying drawings are: FIG. 1 is a block diagram showing an overall configuration according to an embodiment of an in-vehicle control system including an in-vehicle controller applicable to a preceding-vehicle selection device; FIG. 2 is a flowchart of a preceding vehicle selection process performed by the vehicle-to-vehicle controller shown in FIG. 1 ; FIG. 3 is a diagram showing the contents of a correction coefficient table used for setting a correction coefficient; FIG. 4 is an explanatory diagram showing the function of the correction coefficients; FIG. 5 is an explanatory diagram showing the effects of correction of the lateral position; and FIG. 6 is a block diagram showing a functional configuration of the vehicle-to-vehicle controller shown in FIG. 1.An embodiment to which the present invention is applied will be explained below with reference to the drawings.A vehicle-to-vehicle control system 1 is installed in a car. The inter-vehicle control system 1 controls the vehicle speed of a vehicle (hereinafter, also referred to as a subject vehicle for short) to maintain a vehicle-to-vehicle distance between the subject vehicle and a vehicle traveling in front of the subject vehicle (hereinafter, also referred to as a "preceding vehicle" for short) at an appropriate distance. With the subject vehicle as a reference point, this distance is also referred to below as a distance "to the preceding vehicle" for short.As shown in FIG. 1, the in-vehicle control system 1 basically includes an in-vehicle controller 4 serving as a preceding-vehicle selection device according to the embodiment. The in-vehicle control system 1 further includes a sensor group 2, a switch group 3, and a group 5 including various electronic control / regulation units (ECU). The sensor group 2 includes various sensors used to detect the surroundings of the vehicle as well as the behavior and state of the vehicle. The switch group 3 includes various switches used to input instructions or instructions to the vehicle-to-vehicle controller 4. The ECU group 5 performs various controls based on commands from the in-vehicle controller 4.The sensor group 2 includes at least a radar sensor 21, a yaw rate sensor 22, a wheel speed sensor 23, and a steering sensor 24.The radar sensor 21 emits a laser beam into a (preceding) area located in front of the subject vehicle to thereby scan a predetermined angular range. Radar sensor 21 also detects a reflected light of the emitted laser beam. The radar sensor 21 determines the distance to an object that has reflected the laser beam, based on the time period required for the laser beam to travel to the object and the time period required for the reflected light of the laser beam to travel from the object back to the subject vehicle. Further, the radar sensor 21 determines the direction in which the object is located based on the direction in which the laser beam is irradiated when the reflected light is detected. The sensor 21 is not limited to a radar sensor 21 using laser light, but may be a sensor using millimeter-band or micrometer-band radio or radio waves, ultrasonic waves, or the like. Further, a camera or the like may be used.Wheel speed sensors 23 are attached to the front left wheel, the front right wheel, the rear left wheel, and the rear right wheel. Each wheel speed sensor 23 outputs a pulse signal having a flank (pulse flank) generated at predetermined rotational angles of the wheel shaft. In other words, the wheel speed sensor 23 outputs a pulse signal having a pulse interval with time depending on the rotational speed of the wheel shaft.The steering sensor 24 outputs signals based on a relative steering angle of a steering wheel (change amount of a steering angle) or an absolute steering angle of the steering wheel (actual steering angle with respect to a steering position when the vehicle is traveling straight).The switch group 3 includes at least a control permission switch 31 and a control mode selection switch 32.The control permission switch 31 is used to input whether or not execution of adaptive cruise control (ACC) is permitted. The ACC is a known control that allows the subject vehicle to travel at a predetermined speed when no vehicle (preceding vehicle) is traveling ahead of it. The ACC performs a follow-up control in which a predetermined inter-vehicle distance is maintained when a preceding vehicle is present.The control mode selection switch 32 is used to select an ACC control mode.The ECU group 5 includes at least an engine ECU 51, a brake ECU 52, and a measurement ECU 53.The engine ECU 51 controls an engine start / stop, a fuel injection amount, an ignition sequence, and the like. The engine ECU 51 includes a central processing unit (CPU), a read only memory (ROM), a random access memory (RAM), and the like. Specifically, the engine ECU 51 controls a throttle ACT based on detection values from a sensor that detects the depression amount of an accelerator pedal. The throttle ACT is an actuator that opens and closes a throttle disposed in an air intake passage. Further, the engine ECU 51 controls the throttle ACT to increase and decrease the driving force of an internal combustion engine on the basis of instructions from the in-vehicle controller 4.The brake ECU 52 controls the braking operation of the subject vehicle. The brake ECU 52 includes a CPU, a ROM, a RAM, and the like. Specifically, the brake ECU 52 controls a brake ACT based on detection values from a sensor that detects a depression amount of a brake pedal. The brake ACT is an actuator that opens and closes a pressure increase control valve and a pressure decrease control valve that are disposed in a hydraulic brake circuit. Further, the brake ECU 52 controls the brake ACT to increase and decrease a braking force of the subject vehicle based on instructions from the vehicle-vehicle controller 4.The meter ECU 53 performs display control of a meter display disposed in the vehicle on the basis of instructions from the units of the vehicle including the vehicle-to-vehicle controller 4. The measurement ECU 53 includes a CPU, a ROM, a RAM, and the like. Specifically, the measurement ECU 53 displays, on the measurement display, the vehicle speed, the engine speed, and the execution state and the control mode of the control performed by the in-vehicle controller 4.The in-vehicle controller 4 is basically configured as a known microcomputer including a CPU, a ROM, a RAM, and the like. Further, the vehicle-to-vehicle controller 4 includes a detection circuit, an analog / digital (A / D) conversion circuit, an input / output (I / O) interface, a communication circuit, and the like. The detection circuit and the A / D conversion circuit detect signals output from the sensor group 2 and convert these signals into digital values. The I / O interface receives input signals from the switch group 3. The communication circuit communicates with the ECU group 5. Therefore, detailed description is omitted here.In the in-vehicle controller 4, the CPU executes one or more programs stored in advance in the memory (e.g., the ROM) to perform a predetermined in-vehicle determination process, as described in detail below. Thus, as shown in FIG. 6, the vehicle-to-vehicle controller 4 is capable of serving as the preceding vehicle selection device including an object detection unit 41 (equivalent to the object detection means), a sideways movement speed calculation unit 42 (equivalent to the sideways movement speed calculation means), a sideways position correction unit 43 (equivalent to the sideways position correction means), a subject vehicle lane probability calculation unit 44 (equivalent to the subject vehicle lane probability calculation means), and a preceding vehicle selection unit 45 (equivalent to the preceding vehicle selection means).When the ACC is permitted by the control permission switch 31, the in-vehicle controller 4 periodically (about every 100 msec) performs a preceding-vehicle determination process. Further, the in-vehicle controller 4 performs an in-vehicle control process selected by the control mode selection switch 32 using the determination result of the preceding-vehicle determination process.Among the processes, in the in-vehicle control process, the in-vehicle controller 4 usually controls the vehicle speed by outputting instructions for increasing and decreasing the accelerator operation amount to the engine ECU 51. When control using the accelerator operation amount cannot be supported, the in-vehicle controller 4 limits the vehicle speed by outputting a brake command to the brake ECU 52. Further, the in-vehicle controller 4 outputs various ACC-related display information and commands for generating a warning signal to the measurement ECU 53 when predetermined conditions are satisfied.Next, details of the preceding vehicle determination process performed by the in-vehicle controller 4 will be described with reference to the flowchart shown in FIG. 2. In the embodiment, a program that allows the CPU of the in-vehicle controller 4 to perform the in-vehicle determination process shown in FIG. 2 has been stored in advance in the memory (e.g., the ROM) of the in-vehicle controller 4.When the preceding vehicle determination process is started, the vehicle-to-vehicle controller 4 firstly loads the distance and angle measurement data detected by the radar sensor 21 in step S 110.In the following step S 120, the inter-vehicle controller 4 converts the loaded distance and angle measurement data from the polar coordinate system expressed by the data into an orthogonal coordinate system. Based on the converted data, the vehicle-to-vehicle controller 4 performs an object recognition process to recognize a (ahead) object located in front of the subject vehicle. In the object recognition process, the vehicle-to-vehicle controller 4 groups (clusters) the distance and angle measurement data. The vehicle-to-vehicle controller 4 then determines the center coordinates of the object, the relative speed with respect to the subject vehicle, and the like for each group (each cluster). The object (corresponding to a preceding object) recognized here is referred to as a "target" below. The in-vehicle controller 4 performs the processing in step S 120 and is then capable of serving as the object position detection unit 41 in FIG. 6.In the following step S 130, an estimated turning radius R is calculated based on the following equation (1) based on the yaw rate γ detected by the yaw rate sensor 22 and the subject vehicle speed V calculated based on the detection results from the wheel speed sensors 23. The estimation curve radius R is the curve radius (inverse of the curvature) of a subject vehicle traveling curve.In steps S 140 to S 190 described below, the same process is executed for all the targets acquired in step S 120 (object recognition process).In the following step S 140, the vehicle-to-vehicle controller 4 uses the curve radius R estimated in step S 130 to convert the center coordinates of the target into position coordinates on the premise that the road on which the subject vehicle travels is a straight road. Here, in order to simplify the process, let the vehicle width direction be the X axis and the traveling direction of the vehicle perpendicular to the vehicle width direction be the Y axis. Only the position coordinate in the X-axis direction (referred to herein as lateral position) can be converted.In the following step S 150, the in-vehicle controller 4 calculates a sideways movement speed (movement speed in the X-axis direction) based on the difference between the sideways position calculated in step S 140 and the sideways position obtained in the previous processing cycle. The in-vehicle controller 4 executes the processing in step S 150 and is then capable of serving as the lateral movement speed calculation unit 42 in FIG. 6.In the following step S 160, the in-vehicle controller 4 determines a correction coefficient α from the distance to the target (which may be replaced with the position coordinate in the Y-axis direction). The correction coefficient α is calculated using a correction coefficient table prepared in advance.As shown in FIG. 3, the correction coefficient table is created such that the correction coefficient α is a predetermined upper limit value when the distance to the target is less than a close distance threshold La. The correction coefficient α is a predetermined lower limit value when the distance to the target is larger than a remote distance threshold Lb. When the distance to the target is the near distance threshold La or a larger distance and at the same time the far distance threshold Lb or a smaller distance, the correction coefficient α is set to decrease from the upper limit value to the smaller limit value as the distance to the target increases.In the following step S 170, the in-vehicle controller 4 calculates a corrected lateral position Xr of the lateral position X determined in step S 140 based on the lateral movement speed Vx determined in step S 150 and the correction coefficient α determined in step S 160 using the following equationHere, Tp is a constant with the dimension of time. In other words, Equation (2) corresponds to a determination based on the lateral movement speed Vx of a predicted position when the time Tp has elapsed from the present time point. However, as shown in FIG. 4, as a result of the correction coefficient α, the amount of correction becomes more limited as the distance to the target increases even if the lateral movement speed Vx is the same. The in-vehicle controller 4 performs the processing in steps S 160 and S 170, and is then capable of serving as the lateral position correction unit 43 in FIG. 6.The center position coordinates of the target that have been converted in step S 140 and whose lateral position has been corrected in step S 170 are referred to herein as "probability calculation position coordinates".In the following step S 180, the vehicle-to-vehicle controller 4 calculates a subject vehicle lane probability present value for each target on the basis of the probability calculation position coordinates. The subject vehicle lane probability current value is calculated using a subject vehicle lane probability map prepared in advance. The subject vehicle lane probability is a parameter that is a measure of the probability of the target being a vehicle traveling in the same lane as the subject vehicle. The subject vehicle lane probability instantaneous value is an instantaneous value of the subject vehicle lane probability calculated based on detection data of the current processing cycle.The subject vehicle lane probability map is a known map in which the probability tends to be highest when the probability calculation position coordinates are located near a front-continuing longitudinal axis of the subject vehicle and at a short distance from the latter. Further, the likelihood tends to be less the farther away and laterally offset from the forward-continuing longitudinal axis of the subject vehicle the likelihood calculation position coordinates are. A specific example and a specific use of the subject vehicle lane probability map are described in detail in JP 3 427 815 B2.One reason for expressing whether or not the target is in the lane of the subject vehicle in the form of a probability is to assume a deviation between the curvature radius of the curvature (estimated curvature radius R) determined from the yaw rate and the actual curvature radius of the curvature.In the following step S 190, the vehicle-to-vehicle controller 4 calculates a subject vehicle lane probability for each destination. The subject vehicle lane probability is calculated by the vehicle-vehicle controller 4 performing a filter calculation on the subject vehicle lane probability current value determined in step S 180. The subject vehicle lane probability is used for determining the preceding vehicle. The filter obtained by the filter calculation is only required to be a so-called low-pass filter. For example, a weighted average of the subject vehicle lane probability instantaneous value and the subject vehicle lane probability determined in the previous processing cycle may be calculated. The in-vehicle controller 4 performs the processing of steps S 180 and S 190 and is then capable of serving as the subject vehicle lane probability calculation unit 44 in FIG. 6.In the following step S 200, the vehicle-to-vehicle controller 4 determines the preceding vehicle on the basis of the subject vehicle lane probability calculated in step S 190. The vehicle-to-vehicle controller 4 then ends the process. Specifically, for example, the in-vehicle controller 4 determines a target from the targets whose subject vehicle lane probability P(t) has a threshold value (such as 50%) or above that is the shortest distance from the subject vehicle as the preceding vehicle. The in-vehicle controller 4 performs the processing in step S 200, and is then capable of serving as the preceding-vehicle selection unit 45 in FIG. 6.Then, the in-vehicle controller 4 performs the in-vehicle control process on the basis of the distance to the target determined as the forward vehicle by the forward vehicle determination process and the relative speed with respect to the target. The in-vehicle controller 4 outputs various commands to the ECU group 5.As shown in FIG. 5, the lateral movement speed Vx of the target when the target (a preceding vehicle) travels in an adjacent lane is substantially zero. Therefore, the detected lateral position and the corrected lateral position are substantially identical. When the target attempts to change the lane to that of the subject vehicle and approaches the lane of the subject vehicle, the lateral movement speed Vx holds a value.Therefore, the sideways position is corrected to a position closer to the lane of the subject vehicle by an amount based on the sideways movement speed Vx. Therefore, the cut-in vehicle can be immediately identified as the preceding vehicle. Subsequently, when the lane change is completed, the lateral movement speed Vx again becomes substantially zero. Therefore, the detected lateral position and the corrected lateral position are substantially identical.Conversely, when the target changes from the driving lane of the subject vehicle to the adjacent driving lane, the sideways position is corrected to a position farther from the driving lane of the subject vehicle, again based on the sideways moving speed Vx (not shown). As a result, the selection of the preceding vehicle can be immediately deleted.As described above, in the vehicle-vehicle system 1, the subject vehicle lane probability is calculated and the preceding vehicle is selected using the lateral position Xr corrected using the lateral movement speed Vx. In other words, the predicted lateral position is used after a lapse of a certain period of time Tp. Therefore, a vehicle that enters or leaves the lane of the subject vehicle can be determined at an early time. The responsiveness of selection and cancellation of selection of a preceding vehicle can be improved.Further, using the correction amount α, the larger the distance becomes, the smaller the amount of correction of the lateral position becomes. Therefore, wrong determination at long distances where errors increase with increasing distance can be prevented, while early determination at near distances can be ensured.(Other Embodiments)An embodiment of the present invention is described above. However, the present invention is not limited to the above-described embodiment, but various other embodiments are possible as a matter of course. (1) According to the above-described embodiment, the estimation radius of curvature R is calculated from the yaw rate detected by the yaw rate sensor. However, the estimation radius of curvature R may be calculated from the steering angle detected by the steering sensor. (2) According to the above-described embodiment, a dimensionless correction coefficient a is used for calculation of the corrected lateral position Xr and multiplied by the predicted lateral position (Vx×Tp). However, a correction coefficient β (=α×Tp) may also be used with the dimension of time and multiplied by the lateral movement speed Vx. In this case, the corrected lateral position Xr may be calculated by the following equation (3). (3) According to the above-described embodiment, an example is given in which the present invention is applied to an in-vehicle control system. However, the present invention is not limited thereto, but may be applied to any system as long as the system sets a preceding vehicle and performs any control based on the state of the preceding vehicle or the relative state between the preceding vehicle and the subject vehicle. (4) The elements of the present invention are conceptual and not limited to those according to the present embodiment. For example, functions provided by a single element may be divided into a plurality of elements. Alternatively, the functions of multiple elements may be combined into a single element. Further, at least some of the configurations according to the above-described embodiment may be replaced with a known configuration having similar functions. Further, at least some of the configurations according to the above-described embodiment may be added or replaced with other configurations according to the above-described embodiment, for example.

Claims

A preceding vehicle selection apparatus comprising: object detection means (4, 41, S120) that detects an object in front of a subject vehicle and determines a relative position and a relative speed with respect to the subject vehicle for each preceding object; lateral movement speed calculation means (4, 42, S150) that calculates a lateral movement speed of the preceding object on the basis of detection results of the preceding object detected by the object detection means; lateral position correction means (4, 43, S160, S170) that corrects the lateral position of the preceding object with respect to a traveling direction of the subject vehicle on the basis of the lateral movement speed calculated by the lateral movement speed calculation means; a subject vehicle lane probability calculation means (4, 44, S180, S190) that calculates a subject vehicle lane probability for each subject object based on the relative position of the subject object whose lateral position has been corrected by the lateral position correction means, wherein the subject vehicle lane probability is a probability that the subject object is in the same lane as the subject vehicle; and a preceding vehicle selection means (4, 45, S200) that selects a preceding vehicle from the preceding objects on the basis of the subject vehicle lane probability calculated by the subject vehicle lane probability calculation means, wherein the lateral position correction means corrects the lateral position of the preceding object on the basis of a distance to the preceding object such that a correction amount of the lateral position decreases as the distance to the preceding object increases.The preceding vehicle selection device according to claim 1, wherein the sideways position correction means corrects the sideways position by adding a correction value to the sideways position, the correction value being a value obtained by multiplying the relative speed by a correction coefficient that changes depending on the distance to the preceding object.The preceding vehicle selection device according to claim 2, wherein: - the correction coefficient is set to a predetermined upper limit value when the distance to the preceding object is less than a first close distance threshold; - the correction coefficient is set to a predetermined lower limit value when the distance to the preceding object is greater than a second remote distance threshold; and - the correction coefficient is set to decrease from the upper limit value to the lower limit value as the distance to the preceding object increases, when the distance to the preceding object is the first threshold or greater and the threshold or less.The preceding vehicle selection device according to claim 3, wherein the corrected lateral position is determined by X r = X + α × V x × T p wherein: X is a lateral position, α is a dimensionless correction coefficient, Vx is a lateral movement speed, Tp is a constant with the dimension time, and Xr is a corrected lateral position of the lateral position X.The preceding vehicle selection device according to claim 3, wherein the corrected lateral position is determined by X r = X + β × V x wherein: X is a lateral position, β is a correction coefficient with the dimension time, Vx is a lateral movement speed, and Xr is a corrected lateral position of the lateral position X.A preceding vehicle selection method comprising the steps of: - detecting, by a preceding vehicle selection device, an object in front of the subject vehicle and determining a relative position and a relative speed with respect to the subject vehicle for each preceding object; - calculating, by the preceding vehicle selection device, a sideways movement speed of the preceding object based on detection results of the preceding object; - correcting, by the preceding vehicle selection device, the sideways position of the preceding object with respect to a direction of travel of the subject vehicle based on the calculated sideways movement speed; calculating, by the preceding vehicle selection device, a subject vehicle lane probability for each preceding object based on the relative position of the preceding object whose lateral position has been corrected, the subject vehicle lane probability being a probability that the preceding object is in the same lane as the subject vehicle; selecting a preceding vehicle from the preceding objects based on the calculated subject vehicle lane probability; and correcting, by the preceding vehicle selection device, the lateral position of the preceding object based on a distance to the preceding object such that a correction amount of the lateral position decreases as the distance to the preceding object increases.The preceding vehicle selection method according to claim 6, wherein the sideways position is corrected by adding a correction value to the sideways position, the correction value being a value obtained by multiplying the relative speed by a correction coefficient that changes depending on the distance to the preceding object.The preceding vehicle selection method according to claim 7, wherein: - the correction coefficient is set to a predetermined upper limit value when the distance to the preceding object is less than a first close distance threshold; - the correction coefficient is set to a predetermined lower limit value when the distance to the preceding object is greater than a second remote distance threshold; and - the correction coefficient is set to decrease from the upper limit value to the lower limit value as the distance to the preceding object increases, when the distance to the preceding object is the first threshold or greater and the threshold or less.The preceding vehicle selection method according to claim 8, wherein the corrected lateral position is determined by X r = X + α × V x × T p wherein: X is a lateral position, α is a dimensionless correction coefficient, Vx is a lateral movement speed, Tp is a constant with the dimension time, and Xr is a corrected lateral position of the lateral position X.The preceding vehicle selection method according to claim 8, wherein the corrected lateral position is determined by X r = X + β × V x wherein: X is a lateral position, β is a correction coefficient with the dimension time, Vx is a lateral movement speed, and Xr is a corrected lateral position of the lateral position X.

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