VEHICLE SPEED CONTROL DEVICE, VEHICLE SPEED CONTROL METHOD AND VEHICLE SPEED CONTROL PROGRAM

Abstract

Vehicle speed control device (10) for controlling the movement of one's own vehicle (M1) on the basis of a predicted course, which is a future course of the own vehicle (M1), the device comprising: a position storage device (25a) for chronologically storing a position of a vehicle ahead, which is a position of a vehicle (M2) moving ahead of the vehicle (M1); a course calculation device (21) for calculating the predicted course based on a motion path of the advance vehicle position stored in the position storage device (25a); and a position update device (25c) for updating each value stored in the position storage device (25a) each time a motion path of the preceding vehicle (M2) is calculated, wherein The position update device (25c) receives a radius of curvature (R) of a road on which the own vehicle (M1) is moving, wherein the radius of curvature (R) is estimated on the basis of a speed and a yaw rate of the own vehicle (M1), performs a coordinate transformation of the advance vehicle position stored in the position storage device (25a) on the basis of the received radius of curvature (R), and updates the value of the advance vehicle position after the coordinate transformation as the previous value.

Description

[0001] The invention relates to a vehicle speed control technology for controlling the movement of one's own vehicle based on a predicted course of the vehicle.

[0002] A vehicle following control system, a well-known type of adaptive cruise control, instructs the vehicle to follow a vehicle traveling in the same lane among the vehicles ahead. In such a system, it is crucial that a vehicle traveling in the same lane is identified with high accuracy from among the vehicles ahead, as detected by a sensor or camera. Therefore, a vehicle on a calculated future path of the vehicle is conventionally used as the target for the following control system. Various methods exist for calculating this future path.

[0003] A method and a device for determining the future course of a first vehicle equipped with a distance sensor are known from German patent application DE 198 55 400 A1. Using the distance sensor, the relative positions of at least one preceding vehicle to the first vehicle are determined at fixed or selectable times. These determined relative positions are stored in at least one memory location. Each of these relative positions stored in the memory location represents a course of the corresponding preceding vehicle. The future course of the first vehicle is determined based on the course of the preceding vehicle. The course of the preceding vehicle is projected towards the position of the first vehicle.

[0004] Furthermore, German patent application DE 10 2010 023 196 A1 discloses a method and a device for detecting vehicles ahead. This method, executable in an adaptive cruise control (ACC) device of a motor vehicle, for assessing whether another vehicle is ahead of the vehicle in its lane, comprises the following steps: measuring the position of the other vehicle in a coordinate system referenced to the vehicle at a given time; monitoring the development of the distance between the vehicle and the measured position; and assessing the other vehicle as being ahead if the distance falls below a predetermined lower limit.

[0005] Patent document JP 2002-531 886 A further discloses a method that involves storing the trajectory of a vehicle moving ahead of the user's own vehicle and calculating a future course of the user's own vehicle based on the stored trajectory. According to patent document JP 2002-531 886 A, the shape of the road is estimated based on the trajectory of a preceding vehicle in the same lane as the user's own vehicle when the user's own vehicle is following the preceding vehicle, and the result of this estimate is used as a future course of the user's own vehicle. The technique described in patent document 1 does not account for the case in which the user's own vehicle or the preceding vehicle changes course, in which case an incorrect course could be calculated as a predicted course of the user's own vehicle.

[0006] The invention is based on the objective of providing a vehicle speed control technology that prevents a decrease in the accuracy of predicting the course of the vehicle itself.

[0007] This problem is solved by a vehicle speed control device with the features of claim 1, a vehicle speed control method with the features of claim 9, and a vehicle speed control program with the features of claim 10. Advantageous embodiments are the subject of the appended dependent claims.

[0008] The invention thus relates to a vehicle speed control device for controlling the movement of one's own vehicle based on a predicted course, which is a future course of the own vehicle. The device comprises a position storage device for chronologically storing a position of a vehicle ahead, which is the position of a vehicle moving in front of the own vehicle; a course calculation device for calculating the predicted course based on a trajectory of the position of the vehicle ahead stored in the position storage device; and a position update device for updating each value stored in the position storage device each time a trajectory of the vehicle ahead is calculated.The position update device receives a radius of curvature of a road on which the own vehicle is moving, the radius of curvature being estimated based on a speed and yaw rate of the own vehicle, performs a coordinate transformation of the ahead vehicle position stored in the position storage device based on the received radius of curvature using a rotation matrix, and updates the value of the ahead vehicle position after the coordinate transformation as the previous value.

[0009] During actual driving, the driver of any vehicle can alter its current course by turning right or left or by changing lanes, potentially resulting in a situation unsuitable for calculating the trajectory of the vehicle ahead. In such cases, the prediction may fail to provide a highly accurate result, leading to reduced controllability of the driving assistance system.

[0010] In light of this, the vehicle speed control device of this invention is configured to cancel or override the positions of vehicles ahead that indicate the path of travel of a vehicle ahead when it is determined that either the vehicle being driven or the vehicle ahead is in a situation where there is a probability that the vehicle being driven or the vehicle ahead will deviate from its current course. If the course of the vehicle being driven is predicted using data obtained in a situation where either the vehicle being driven or the vehicle ahead has deviated from its current course, that is, has not been moving along the lane or road, the accuracy of the prediction may decrease.In accordance with the above configuration, the vehicle speed control device of this invention prevents a decrease in the accuracy of predicting the course of its own vehicle.

[0011] The vehicle speed control device of this invention includes a position memory device for chronologically storing a value of the position of a vehicle ahead, which is the position of a vehicle moving in front of the vehicle being controlled, and a course calculation device for calculating a predicted course of the vehicle being controlled based on the trajectory of the positions of vehicles ahead chronologically stored in the position memory device. The vehicle speed control device further includes a position update device for updating, as the preceding value, each value of the positions of vehicles ahead chronologically stored in the position memory device every time the trajectory of the vehicle ahead is calculated.The position update device performs a coordinate transformation of the advance vehicle positions stored chronologically in the position memory device based on the speed and yaw rate of its own vehicle, and each of the values ​​of the advance vehicle positions that have undergone the coordinate transformation is updated as the preceding value.

[0012] During actual driving, a vehicle may travel not only on a straight road and a road with gentle curves, but also on a road with complex curves, such as an S-shaped bend. On such a road with complex curves, the accuracy of calculating the trajectory of a vehicle ahead may decrease. In this case, the prediction may fail to provide a highly accurate result, thus reducing the controllability of a driver assistance system.

[0013] In light of this, the vehicle speed control device of this invention is configured to perform a coordinate transformation of the positions of the vehicles ahead on a time-series basis, using the speed and yaw rate of the vehicle being controlled, and to update each value of the positions of the vehicles ahead as the preceding value. This configuration enables the determination of the position of the vehicle ahead relative to (i.e., with reference to) the position of the vehicle being controlled at any given time during the vehicle's movement, and thus allows for a more accurate calculation of the vehicle's trajectory when the vehicle is turning or veering. Consequently, the course of the vehicle being controlled can be predicted more accurately. Fig. Figure 1 is a block diagram that represents a schematic configuration of a vehicle speed control device. Fig. 2 represents a method for calculating a predicted course of one's own vehicle. Fig. Figure 3 represents the position and trajectory of a vehicle traveling ahead. Fig. 4 represents a process of updating the positions of the vehicles ahead. Fig. Figure 5 is a flowchart of a procedure for calculating the trajectory of the vehicle ahead.

[0014] An embodiment of a vehicle speed control device is described below with reference to the drawings. The vehicle speed control device according to this embodiment is attached to or installed on a vehicle. The vehicle speed control device performs a vehicle following control to cause the vehicle to follow a vehicle traveling in the same lane as the vehicle ahead, even when the vehicle is traveling in front of it. The vehicle following control maintains a following distance between the vehicle and the vehicle ahead. The following is described below with reference to Fig. 1 A schematic configuration of the vehicle speed control device of the present embodiment is described.

[0015] A vehicle speed control device 10 of Fig. 1 is a computer with a CPU, a ROM, a RAM, and an input / output (I / O) port. The vehicle speed control device 10 includes a course prediction section 20, a following vehicle determination unit 35, and a control setpoint calculation unit 36. The CPU executes a program installed in the ROM to implement these functions. The vehicle (the own vehicle) includes an object detection device for detecting an object in the vicinity of the vehicle. The vehicle speed control device 10 receives information about a detected object from the object detection device and performs vehicle tracking control based on the supplied information to cause the own vehicle to follow the vehicle ahead. The own vehicle includes an imaging device 11 and a radar device 12, each of which serves as the object detection device.

[0016] The imaging device 11 is a vehicle-mounted camera comprising a CCD camera, a CMOS image sensor, and a near-infrared camera. The imaging device 11 captures an image of the surrounding environment, including the road on which the vehicle is traveling, generates image data representing the captured image, and outputs the data sequentially to the vehicle cruise control device 10. The imaging device 11, which may be installed near the top of the vehicle's windshield, captures a region extending in front of the vehicle at a predetermined angle θ1 to the imaging axis of the imaging device 11, with the imaging axis being used as the center of the region. The imaging device 11 may be a monocular or a stereo camera.

[0017] The radar device 12 is a detection device that emits electromagnetic waves as transmitted or transmitted waves (monitoring waves) and detects an object upon receiving the reflected wave. The radar device 12 of the present embodiment is a millimeter-wave radar. Using radar signals, the radar device 12, mounted on the front of the vehicle, searches for or scans a region extending in front of the vehicle at a predetermined angle θ2 (θ2 < θ1) from the optical axis of the radar device 12, the optical axis being used as the center of the region. The radar device 12 then generates distance or...Distance measurement data is calculated based on the time it takes for the electromagnetic waves emitted in the forward direction of the vehicle to return to the radar device 12, and the generated distance measurement data is output sequentially to the vehicle cruise control device 10. The distance measurement data contains information about the direction in which the object is located, the distance between the vehicle and the object, and the relative speed between the vehicle and the object. The radar device 12 corresponds to the "following distance sensor".

[0018] In the vehicle ready for delivery, the imaging device 11 and the radar device 12 are mounted such that the imaging axis, which is a reference axis, of the imaging device 11 and the optical axis, which is also a reference axis, of the radar device 12 run parallel to a road surface on which the vehicle is traveling. The detection ranges of the imaging device 11 and the radar device 12 partially overlap.

[0019] The vehicle cruise control device 10 receives image data from the imaging device 11, distance measurement data from the radar device 12, and a signal from various types of sensors mounted on the vehicle, including a yaw rate sensor 13 for detecting the angular velocity (hereinafter referred to as a "yaw rate") of the rotating vehicle and a vehicle speed sensor 14 for detecting the vehicle speed. Also provided are a steering angle sensor 15 for detecting the steering angle and a driver-operated ACC switch or automatic cruise control control switch 16 for selecting a vehicle following control operating mode. The vehicle further includes a direction indicator 17, which allows the direction in which the vehicle is moving to be displayed outside the vehicle.The direction indicator 17 includes an actuating lever which is manipulated by a driver into a left direction indicator position, a neutral position or a right direction indicator position, and outputs an actuating signal to the vehicle speed control device 10 according to the position of the actuating lever.

[0020] The course prediction section 20 is a calculation unit that predicts the future course of the own vehicle. Course prediction section 20 includes a stationary object information acquisition unit 23, a white line information acquisition unit 24, an other vehicle movement path acquisition unit, a curvature radius estimation unit 26, a predictive course calculation unit 21, and a override determination unit 27. Course prediction section 20 predicts the course of the own vehicle based on the movement path of the vehicle ahead of it.

[0021] The stationary object information unit 23 calculates, based on distance measurement data from the radar unit 12, information about the position of a stationary roadside object (for example, a guardrail or a wall) located along the road on which the vehicle is traveling, and outputs the calculated information to the predictive course calculation unit 21 as stationary object information. The white line information unit 24 calculates information about a road boundary line (white line) contained in the image acquired by the imaging unit 11, based on the image data from the imaging unit 11, and outputs the calculated information to the predictive course calculation unit 21 as white line information.More specifically, the process of calculating whiteline information can involve extracting edge points that are candidates for a whiteline from the image data, for example based on a rate of change of luminance in a horizontal direction of the image, sequentially storing the extracted edge points on an image-wise or frame-wise basis, and calculating whiteline information based on the recording of the stored edge points of the whiteline.

[0022] The other vehicle trajectory acquisition section 25 cyclically calculates the position of the vehicle ahead, which is a set of coordinates indicating a point passed by the vehicle ahead, based on distance measurement data from radar unit 12 (information about the distance and lateral position of the own vehicle and the vehicle ahead), and stores the calculated position of the vehicle ahead chronologically. Furthermore, the other vehicle trajectory acquisition section 25 calculates the trajectory of the vehicle ahead based on time-series data about the stored positions of the vehicles ahead and outputs the calculated trajectory to the predictive course calculation unit 21 as other vehicle trajectory information.It is noted that the other vehicle trajectory acquisition section 25 can calculate information about the trajectory of a vehicle traveling in a lane adjacent to the own vehicle, in addition to that of a vehicle traveling in the same lane as the own vehicle, and this information can be used to predict the course of the own vehicle. The curvature radius estimation unit 26 calculates the radius of curvature of the road on which the own vehicle is traveling (hereinafter referred to as "estimated R") based on the yaw angle detected by the yaw rate sensor 13 and the vehicle speed detected by the vehicle speed sensor 14.The estimated R can be calculated using image data, or can be calculated based on the steering angle detected by the steering angle sensor 15 and the vehicle speed detected by the vehicle speed sensor 14.

[0023] The Predictive Course Calculation Unit 21 receives stationary object information from the Stationary Object Information Acquisition Unit 23, white line information from the white line information acquisition unit 24, and other vehicle movement path information from the other vehicle movement path acquisition section 25. The Predictive Course Calculation Unit 21 combines this input information to calculate a predicted course RA, which is a predicted value of a future course of the own vehicle. It is noted that the Predictive Course Calculation Unit 21 can calculate the course of the own vehicle without using the yaw rate of the own vehicle.

[0024] Fig. Figure 2 schematically represents a procedure for calculating a predicted rate RA at the prediction rate calculation unit 21. Fig. 2 (a) represents a multitude of stationary object detection points Pa, which are the results of the radar device 12 detecting a massive obstacle, which is a stationary roadside object (for example, a guardrail). Fig. 2 (b) represents white line information Pb, which is the result of the imaging device 11 that detects a white line. Fig. 2 (c) represents a recording of a multitude of vehicle detection points Pc, which are the results of the radar device 12 detecting a preceding vehicle M2. In addition, Fig. 2 (c) represents two different vehicles ahead: a vehicle ahead traveling in the same lane as the vehicle M1; and a vehicle ahead traveling in a lane adjacent to the vehicle M1. Fig. 2 (d) represents a predicted course RA calculated using the stationary object detection points Pa, the white line information Pb and the vehicle detection points Pc.

[0025] The predictive course calculation unit 21 first compares the trajectory of a preceding vehicle M2, calculated from the vehicle detection points Pc, with a white line and a solid obstacle. Predictive course calculation unit 21 excludes (discards) the trajectory of a preceding vehicle M2 if it does not match the shapes of the white line and the solid obstacle. If there is only one non-excluded trajectory of a preceding vehicle M2, predictive course calculation unit 21 uses this non-excluded trajectory to calculate a predicted course RA by weighting and averaging the trajectory of the preceding vehicle M2 and the white line information Pb.If there are multiple non-excluded trajectories of the preceding vehicle M2, the predictive course calculation unit 21 calculates the predicted course RA by weighting and averaging the trajectories of preceding vehicles M2 and the white line information Pb, using a mean of the non-excluded trajectories to calculate the predicted course RA. The predictive course calculation unit 21 corresponds to "the course calculation device".

[0026] Using a predicted course RA of the own vehicle M1, supplied by the course prediction section 20, the followed vehicle designation unit 35 designates a preceding vehicle M2, which is on the predicted course, as a followed vehicle from among the preceding vehicles M2 moving in front of the own vehicle M1. The control setpoint calculation unit 36 ​​calculates a control setpoint, which is used by controlling the speed of the own vehicle M1 to maintain a following distance between the followed vehicle, as determined by the followed vehicle designation unit 35, and the own vehicle M1. The control setpoint calculation unit 36 ​​calculates a control setpoint to maintain a predetermined setpoint distance between the followed vehicle and the own vehicle.More specifically, the control setpoint calculation unit 36 ​​calculates, for example, a target power output of an engine in the vehicle itself or a required braking force, and outputs this to an electronic engine control unit (engine ECU 41). In the present embodiment, the vehicle speed control device 10 outputs a control signal to the engine ECU 41, and the engine ECU 41 outputs the control signal to an electronic brake control unit (brake ECU 42). Alternatively, the vehicle speed control device 10 can output the control signal to either the engine ECU 41 or the brake ECU 42.

[0027] The calculation of the trajectory of the preceding vehicle M2, performed by the vehicle speed control device 10 according to the present embodiment, is described below. The trajectory acquisition section 25 of the present embodiment includes a preceding vehicle position storage unit 25a, a trajectory calculation unit 25b, and a preceding vehicle position update unit 25c.

[0028] The advance vehicle position storage unit 25a calculates the advance vehicle position cyclically based on the distance measurement data from the radar device 12 and stores the calculated advance vehicle position chronologically in a predetermined memory area (storage device). In the present embodiment, vehicle detection points Pc are averaged for each of predetermined distance intervals, and an average value for each distance interval is defined as a value for the advance vehicle position Pd. Fig. Figure 3 represents the leading vehicle positions Pd and the path of motion RT of the leading vehicle M2, which is moving in front of the own vehicle M1. In the present embodiment, as in Fig. Figure 3 shows the region in front of the vehicle M1 divided into a multitude of sections at intervals of, for example, 10 meters, and the position of the vehicle ahead, Pd, is calculated for each of the sections. For example, in Fig. 3. An area in front of the vehicle M1 is divided into sections K1-K5. In this case, the advance vehicle position storage unit 35a averages the vehicle detection points Pc in each of the sections K1-K5 to calculate the advance vehicle position Pd. Then, the advance vehicle position storage unit 25a chronologically stores the calculated advance vehicle position of each section. The advance vehicle position storage unit 25a corresponds to "the position storage device".

[0029] The motion path calculation unit 25b reads the time-series data about the leading vehicle position Pd from the leading vehicle position storage unit 15a. Furthermore, the motion path calculation unit 25b determines a straight line representing the motion path of a vehicle starting from the read-out leading vehicle position Pd and uses this straight line as the motion path RT of the leading vehicle M2. In the present embodiment, as in Fig. Figure 3 shows the leading vehicle positions Pd of adjacent sections connected by, for example, a straight line, and the path of motion generated by connecting the straight line is used as the path of motion RT of the leading vehicle M2.

[0030] The advance vehicle position update unit 25c updates, as the preceding value, each value of the advance vehicle positions Pd, which are stored chronologically in the advance vehicle position memory unit 25a, each time the trajectory RT of the advance vehicle M2 is calculated. Specifically, the advance vehicle position update unit 25c receives the speed of the own vehicle M1, detected by the vehicle speed sensor 14, and the yaw rate of the own vehicle M1, detected by the yaw rate sensor 13. The advance vehicle position update unit 25c performs a coordinate transformation of the advance vehicle positions Pd, which are stored chronologically in the advance vehicle position memory unit 25a, based on the vehicle speed and yaw rate. Each of the values ​​of the advance vehicle positions after the coordinate transformation is updated as the preceding value.Each of the values ​​after the update is stored in the forward vehicle position memory unit 25a as the preceding value on a time-serial basis.

[0031] Regarding Fig. 4. Taking up, a procedure for updating the leading vehicle position Pd via coordinate transformation is described below. Fig. Figure 4 represents two points, position Q(i) and position R(i), each of which is the advance vehicle position Pd before the update. The advance vehicle position update unit 25c performs a coordinate transformation of position Q(i) and position R(i) using both a rotation matrix calculated with the virtual center O as the origin and the estimated R calculated based on the velocity and yaw rate of the own vehicle M1. Each value of a position Q(i-1) and a position R(i-1) that has undergone the coordinate transformation is updated as the preceding value of the advance vehicle position Pd.If a straight line connecting the virtual center O and the vehicle M1 is the X-axis, and a straight line orthogonal to the X-axis is the Y-axis, then, as a result of the coordinate transformation, position Q(i) approaches the vehicle M1 by x1 in the X-axis direction and by y1 in the Y-axis direction. Furthermore, as a result of the coordinate transformation, position R(i) approaches the vehicle M1 by x2 in the X-axis direction and by y2 in the Y-axis direction. Position Q(i-1) and position R(i-1), which are the updated advance vehicle positions Pd, together with the advance vehicle positions Pd calculated based on newly acquired vehicle detection points Pc, are used to calculate the trajectory RT in the next calculation cycle. The advance vehicle position update unit 25c corresponds to "the position update device".

[0032] During actual driving, the driver of any vehicle can change course, potentially resulting in a situation unsuitable for calculating the trajectory RT of the vehicle ahead, M2. If the trajectory RT of the vehicle ahead, M2, is calculated using the positions Pd obtained in the unsuitable situation, and the course of the driver's own vehicle, M1, is predicted in such a case, the prediction may fail to provide a highly accurate result, leading to reduced controllability of the driving assistance system.

[0033] The present embodiment determines whether either the vehicle M1 or the preceding vehicle M2 is in a situation where there is a probability that either the vehicle M1 or the preceding vehicle M2 will deviate from its current course. If it is determined that either the vehicle M1 or the preceding vehicle M2 is in a situation where there is a probability that either the vehicle M1 or the preceding vehicle M2 will deviate from its current course, the preceding vehicle positions Pd stored in the preceding vehicle position memory unit 25a are deleted or overridden.

[0034] As specifically in Fig. As shown in Figure 1, the vehicle 10 of the present embodiment includes a cancellation determination section 27, which serves as a device for canceling or overriding the advance vehicle positions Pd stored in the advance vehicle position storage unit 25a. The cancellation determination section 27 includes a course deviation determination unit 27a and a sensor accuracy determination unit 27b.

[0035] The course deviation determination unit 27a determines whether either the own vehicle M1 or the preceding vehicle M2 is in a situation where there is a probability that the own vehicle M1 or the preceding vehicle M2 will turn left or right, based on the speed of the own vehicle M1 and the preceding vehicle M2. More specifically, it determines whether the preceding vehicle M2 is moving at a low speed (hereinafter referred to as the "first estimation condition") or whether the own vehicle M1 is moving at a low speed (hereinafter referred to as the "second estimation condition").The reason for using the estimation conditions in the investigation procedure is that if the vehicle ahead M2 or the vehicle M1, which is caused to follow the vehicle ahead M2, is moving at a low speed, the vehicles can prepare to turn right or left.

[0036] As used herein, “moving at low speed” is a concept that includes both the fact that a vehicle has slowed down and the fact that a vehicle is moving at low speed. In the present embodiment, the first estimation condition is determined based on distance measurement data from the radar device 12, and the second estimation condition is determined based on a value detected by the vehicle speed sensor 14. The course deviation detection unit 27a outputs an override signal to the other vehicle trajectory acquisition section 25 when it is determined that at least one of the first estimation condition and the second estimation condition has been satisfied.

[0037] The sensor accuracy determination unit 27b uses the distance measurement data from the radar device 12 to determine whether the positions of the vehicle M1 and the vehicle ahead M2 are related in such a way that the detection accuracy of the radar device will decrease. Specifically, it determines whether at least one of the following estimation conditions is met. One estimation condition is that the following distance between the vehicle M1 and the vehicle ahead M2 is extremely large (greater than a predetermined distance) (hereinafter referred to as the "third estimation condition"). Another estimation condition is that the vehicle ahead M2 has deviated from a frontal position of the vehicle M1 and is now within a wide-angle field of view of a sensor (hereinafter referred to as the "fourth estimation condition").Another estimation condition is that the relative speed between the preceding vehicle M2 and the vehicle M1 is high (hereinafter referred to as the "fifth estimation condition"). The sensor accuracy determination unit 27b outputs a cancellation or override signal to the other vehicle trajectory acquisition section 25 if at least one of these estimation conditions is met. The override determination section 27 corresponds to "the override device".

[0038] The other vehicle movement path acquisition section 25 deletes or overrides the advance vehicle positions Pd stored in the advance vehicle position storage unit 25a when the override signal is received by the override determination section 27 (at least one of the course deviation determination unit 27a and the sensor accuracy determination unit 27b). In this case, if a large number of advance vehicles M2 have been detected, all of the advance vehicle positions Pd stored chronologically in the advance vehicle position storage unit 25a can be overridden; alternatively, only the advance vehicle position Pd of an advance vehicle M2 that is likely to deviate from the current course can be overridden. The advance vehicle position Pd can be overridden, for example, by deleting the information about it or prohibiting its use.

[0039] The following describes a process for calculating the trajectory RT of the preceding vehicle M2, which is carried out by the vehicle speed control device 10 of the present embodiment, with reference to the flowchart of Fig. 5 described. This process is carried out by the other vehicle movement path procurement section 25 and the override determination section 27. The vehicle speed control device ECU 10 performs the process cyclically while a vehicle is moving and the ACC switch 16 is turned on.

[0040] Fig. Figure 5 is a flowchart that represents a procedure for calculating the trajectory of the preceding vehicle M2. As in Fig.As shown in Figure 5, in step S101 the vehicle speed control device 10 obtains the leading vehicle position Pd, which was calculated in the current calculation cycle. Next, in step S102, the vehicle speed control device 10 determines whether the leading vehicle M2 is in a situation where there is a probability that the leading vehicle M2 will deviate from the current course (course deviation of the leading vehicle M2). The condition for this determination is that the leading vehicle is traveling at a low speed (whether the first estimation condition is met).If it has been determined that the vehicle ahead M2 is in a situation where there is a probability that the vehicle ahead M2 will deviate from the current course (JA in step S102), the vehicle speed control device 10 initiates the process to proceed to step S107 and overrides the current and previous ahead vehicle positions Pd, which are stored chronologically in the ahead vehicle position memory unit 25a.If the vehicle ahead M2 has slowed down or has been traveling at a low speed (for example, a few km / h to less than 20 km / h) for a predetermined period of time (for example, a few seconds), the vehicle speed control device 10 determines that the vehicle ahead M2 is traveling at a low speed and that the vehicle ahead M2 is in a situation where the vehicle ahead M2 is likely to deviate from its current course.

[0041] If it is determined that the vehicle ahead M2 is not in a situation where it is likely to deviate from its current course (NO in S102), the vehicle speed control device 10 initiates the process to proceed to step S103 and determines whether the own vehicle M1 is in a situation where it is likely to deviate from its current course (own vehicle M1 course deviation). The condition for this determination is that the own vehicle M1 is traveling at a low speed (i.e., the second estimation condition is met).If it is determined that the own vehicle M1 is in a situation where it is likely to deviate from its current course (YES in step S103), the vehicle cruise control device 10 initiates the process to proceed to step S107 and overrides the current and previous ahead vehicle positions Pd, which are stored chronologically in the ahead vehicle position memory unit 25a. If the ahead vehicle or own vehicle M1 has slowed down or has been traveling at a low speed for a predetermined period (for example, a few seconds), the vehicle cruise control device 10 determines that the ahead vehicle or own vehicle M1 is traveling at a low speed and that the own vehicle M1 is in a situation where it is likely to deviate from its current course.

[0042] If it has been determined that the own vehicle M1 is not in a situation where it is likely to deviate from its current course (NO in S103), the vehicle 10 initiates the process to proceed to step S104 and determines whether the positions of the own vehicle M1 and the preceding vehicle M2 satisfy a relationship such that the accuracy of the radar device 12 will decrease. The condition for this determination is any one of the following. The first condition is that the following distance between the own vehicle M1 and the preceding vehicle M2 is extremely large (i.e., the third estimation condition is met). The second condition is that the preceding vehicle M2 has deviated from the frontal position of the own vehicle M1 and is now within a wide-angle field of view of a sensor (i.e., the fourth estimation condition is met).The third condition is that the relative speed between the vehicle ahead M2 and the vehicle itself M1 is high (i.e., the fifth estimation condition is met). If it has been determined that the positions of the vehicle itself M1 and the vehicle ahead M2 satisfy the relationship such that the detection accuracy of the radar device 12 will decrease (YES in step S104), the vehicle speed control device 10 initiates the process to proceed to step S107 and overrides the current and previous ahead vehicle positions Pd, which are stored chronologically in the ahead vehicle position memory unit 25a.

[0043] If it is determined that the positions of the vehicle M1 and the vehicle ahead M2 do not satisfy the relationship such that the detection accuracy of the radar device will decrease (NO in step S104), that is, if the results of steps S102 to S104 are negative, the vehicle speed control device 10 initiates the process to proceed to step S105. In step S105, the vehicle speed control device 10 activates the current and previous ahead vehicle positions Pd, which are stored chronologically in the ahead vehicle position memory unit 25a, and calculates the trajectory RT of the ahead vehicle M2 based on the time-series data on the ahead vehicle positions Pd.Next, in step S106, the vehicle speed control device 10 performs a coordinate transformation of the current and previous advance vehicle positions Pd using a rotation matrix and updates each value of the advance vehicle positions Pd that has undergone the coordinate transformation as the preceding value.

[0044] In accordance with the exemplary embodiment described in detail above, the following advantageous effects can be obtained.

[0045] The vehicle speed control device 10 of the present embodiment is configured to override a leading vehicle position Pd, which is information indicating the trajectory RT of the leading vehicle M2, if it is determined that either the own vehicle M1 or the leading vehicle M2 is in a situation where the own vehicle M1 or the leading vehicle M2 is likely to deviate from its current course. If the course of the own vehicle M1 is predicted using data obtained in a situation where the own vehicle M1 or the leading vehicle M2 has deviated from its current course, that is, has not been moving along the lane or road, the accuracy of the prediction may be reduced.In accordance with the present embodiment, the vehicle speed control device 10 described above can prevent a decrease in the accuracy of the prediction of the course of the own vehicle M1.

[0046] Specifically, the vehicle speed control device 10 of the present embodiment determines whether either the vehicle M1 or the vehicle ahead M2 is in a situation where either the vehicle M1 or the vehicle ahead M2 is likely to turn right or left. The vehicle speed control device 10 is configured to override the ahead vehicle positions Pd, which are stored chronologically in the ahead vehicle position memory unit 25a, when it has been determined that either the vehicle M1 or the vehicle ahead M2 is in a situation where either the vehicle M1 or the vehicle ahead M2 is likely to turn right or left.If the course of the vehicle M1 is predicted using the positions of the vehicles ahead Pd obtained after a right or left turn, it is highly likely that the accuracy in predicting the course of the vehicle M1 will decrease. In view of this, the vehicle speed control device 10 configured above, according to the present embodiment, prevents the accuracy of predicting the course of the vehicle M1 from decreasing when the vehicle ahead M2 or the vehicle M1 turns right or left.

[0047] If either the vehicle M1 or the preceding vehicle M2 is moving at a low speed, the vehicle M1 or the preceding vehicle M2 may prepare to turn right or left. From this perspective, the vehicle speed control device 10, according to the present embodiment, is configured to override the current and previous preceding vehicle positions Pd when it is determined that either the vehicle M1 or the preceding vehicle M2 is moving at a low speed. This configuration is suitable for preventing the course of the vehicle M1 from being predicted using data that could lead to a deterioration in the prediction accuracy.

[0048] For example, if the following distance between the vehicle M1 and the vehicle ahead M2 is extremely large, the vehicle ahead M2 is within the sensor's wide-angle range, and the relative speed between the vehicle M1 and the vehicle ahead M2 is high, the positions of the vehicle M1 and the vehicle ahead M2 will be such that the detection accuracy of the radar device 12 will decrease. In such situations, the vehicle speed control device 10 of the present embodiment overrides the ahead vehicle positions Pd, which are stored in the ahead vehicle position memory unit 25a. This configuration prevents a decrease in the accuracy of predicting the trajectory of the vehicle M1 and is therefore preferable for performing highly accurate vehicle following control.

[0049] The vehicle speed control device according to this embodiment performs a coordinate transformation of the forward vehicle positions Pd on a time-series basis, based on the estimated R calculated from the speed and yaw rate of the own vehicle M1. Each value of the forward vehicle positions after the coordinate transformation is updated as the preceding value. With this configuration, the position of the forward vehicle M2 relative to (in relation to) the position of the own vehicle M1 can be determined at any given time during the movement of the own vehicle M1. Therefore, when the own vehicle M1 rotates, the trajectory RT of the forward vehicle M2 can be calculated more accurately, thus allowing a more precise prediction of the trajectory of the own vehicle M1. (Other possible examples)

[0050] This invention is not limited to the above embodiment and can be implemented as follows.

[0051] • In the preceding embodiment, the predictive course calculation unit 21 receives stationary object information, white line information, and other vehicle trajectory information, and calculates the predicted course RA using these parts of the input information. The predicted course RA can be calculated using, for example, only trajectory information from other vehicles. The predicted course RA can be calculated based on the trajectory information from other vehicles and the stationary object information. The predicted course RA can also be calculated based on the trajectory information from other vehicles and the white line information.

[0052] • In the preceding embodiment, determining whether either the vehicle M1 or the vehicle M2 ahead is in a situation where there is a probability that either the vehicle M1 or the vehicle M2 ahead will turn right or left is based on either the vehicle M1 or the vehicle M2 ahead being traveling at a low speed. Besides vehicle speed, other conditions can be used to determine whether either the vehicle M1 or the vehicle M2 ahead is in a situation where either the vehicle M1 or the vehicle M2 ahead is likely to turn right or left.For example, the condition for the above determination may be that a brake light or a turn indicator of the preceding vehicle M2 has been detected illuminating, and the determination may be based on whether this condition is met. Alternatively, the condition for the determination may be that a brake has been applied to decelerate in the own vehicle M1, or that the turn indicator 17 has been activated in the own vehicle M1, and the determination may be based on whether this condition is met.Alternatively, a combination of the condition that the vehicle M1 or the vehicle M2 ahead is moving at a low speed and the conditions described here can be used to determine whether either the vehicle M1 or the vehicle M2 ahead is in a situation where there is a probability that the vehicle M1 or the vehicle M2 ahead will turn right or left. If the fact that the brake light of the vehicle M2 ahead has illuminated or the fact that the turn signal indicator of the vehicle M2 ahead has illuminated is used as the condition for the determination, it is preferred to use the data from an image captured by the imaging device 11.

[0053] • In the above embodiment, the current and previous leading vehicle positions Pd can be overridden if it has been determined that either the vehicle M1 or the leading vehicle M2 is in a situation where there is a probability that the vehicle M1 or the leading vehicle M2 will change lanes. This is because the lane change can cause the leading vehicle M2 to deviate from the frontal position of the vehicle M1 (enter the wide-angle range of the sensor), which leads to reduced accuracy in the detection.Determining whether either the vehicle M1 or the vehicle M2 ahead is in a situation where there is a probability that the vehicle M1 or the vehicle M2 ahead will change lanes can be done, for example, on the basis of whether the direction indicator of the vehicle M2 ahead has lit up, or whether the direction indicator 17 of the vehicle M1 has been activated.

[0054] • To override the obtained advance vehicle position Pd, other configurations are possible instead of deleting or prohibiting the use of the advance vehicle position Pd stored in the advance vehicle position memory unit 25a. For example, one possible configuration involves deleting the motion path RT, which was calculated using the advance vehicle positions Pd stored in the advance vehicle position memory unit 25a. Another possible configuration involves prohibiting the use of the motion path RT, which was calculated using the advance vehicle positions Pd. A further possible configuration involves deleting or prohibiting the use of the vehicle detection point Pc, which is used to calculate the advance vehicle position Pd.

[0055] • In the preceding embodiment, vehicle detection points Pc are averaged for each predetermined segment, and the mean value of the vehicle detection points Pc is defined as the leading vehicle position Pd. The leading vehicle positions Pd of the adjacent segments are then connected by a straight line to form the path of motion RT of the leading vehicle M2. The leading vehicle position Pd is not limited to the mean value of the vehicle detection points Pc of each predetermined segment. For example, the leading vehicle position Pd can be used as the vehicle detection points Pc. Furthermore, the path of motion RT of the leading vehicle M2 is not limited to the straight line connecting the leading vehicle positions Pd of the adjacent segments. For example, the leading vehicle positions Pc can be averaged to calculate the path of motion RT.

[0056] • In the preceding embodiment, the imaging device 11 and the radar device 12 are provided as the object detection device, but the embodiment is not limited to this configuration, and, for example, a sonar for detecting an object using ultrasonic waves and transmit or transmit waves can be applied to the configuration. Furthermore, the technology of this invention can be applied to a vehicle in which the imaging device 11 is not installed.

[0057] • In the foregoing embodiment, the technology is applied to a vehicle following control system that enables the vehicle to follow the preceding vehicle M2, which is traveling in the same lane as the vehicle M1. The technology of this invention can be applied to a course prediction system for the vehicle M1 to prevent a collision between the vehicle M1 and another vehicle. Furthermore, this invention can be implemented in various modes, such as a program used to instruct a computer to perform each function (each means or device) that constitutes the foregoing vehicle speed control device 10, a medium for storing this program, and a vehicle speed control method. Reference symbol list

[0058] 10...Speed ​​control device, 11...Imaging device, 12...Radar device, 13...Yaw rate sensor, 20...Course prediction unit, 21...Course prediction calculation unit, 23...Stationary object information acquisition unit, 24...White line information acquisition unit, 25...Other vehicle movement path acquisition section, 26...Curve radius estimation unit, 27...Override determination section, 35...Following vehicle determination unit, 36...Control setpoint calculation unit, 41...Engine ECU, 42...Brake ECU

Claims

[1] Vehicle speed control device (10) for controlling the movement of one's own vehicle (M1) on the basis of a predicted course which is a future course of the own vehicle (M1), the device comprising: a position storage device (25a) for chronologically storing a position of a vehicle ahead, which is a position of a vehicle (M2) moving ahead of the vehicle (M1); a course calculation device (21) for calculating the predicted course based on a motion path of the advance vehicle position stored in the position storage device (25a); and a position update device (25c) for updating each value stored in the position storage device (25a) each time a motion path of the preceding vehicle (M2) is calculated, wherein The position update device (25c) receives a radius of curvature (R) of a road on which the own vehicle (M1) is moving, wherein the radius of curvature (R) is estimated on the basis of a speed and a yaw rate of the own vehicle (M1), performs a coordinate transformation of the advance vehicle position stored in the position storage device (25a) on the basis of the received radius of curvature (R), and updates the value of the advance vehicle position after the coordinate transformation as the previous value. [2] Vehicle speed control device according to claim 1, wherein The vehicle speed control device includes a override device (27) for determining whether either the own vehicle (M1) or the vehicle ahead (M2) is in a situation where there is a probability that the own vehicle (M1) or the vehicle ahead (M2) will deviate from the current course, and overriding the position of the vehicle ahead stored in the position memory device (25a) when it has been determined that either the own vehicle (M1) or the vehicle ahead (M2) is in a situation where there is a probability that the own vehicle (M1) or the vehicle ahead (M2) will deviate from the current course, and The override device (27) determines that either the own vehicle (M1) or the vehicle ahead (M2) is in a situation where there is a probability that the own vehicle (M1) or the vehicle ahead (M2) will deviate from the current course if either the own vehicle (M1) or the vehicle ahead (M2) is in a situation where there is a probability that the own vehicle (M1) or the vehicle ahead (M2) will turn right, turn left or change lanes. [3] Vehicle speed control device according to claim 2, wherein the override device (27) determines that either the own vehicle (M1) or the vehicle ahead (M2) is in a situation where there is a probability that the own vehicle (M1) or the vehicle ahead (M2) will deviate from the current course if either the own vehicle (M1) or the vehicle ahead (M2) is moving at a low speed. [4] Vehicle speed control device according to claim 2 or 3, wherein the own vehicle (M1) includes a following distance sensor (12) for detecting a following distance between the own vehicle (M1) and the vehicle ahead (M2) by emitting and receiving search waves, the position storage device (25a) stores the position of the vehicle ahead, which was calculated on the basis of a value detected by the following distance detection sensor (12), and The override device (27) determines whether the positions of the own vehicle (M1) and the vehicle ahead (M2) satisfy a relationship such that the detection accuracy of the following distance sensor (12) will decrease, and overrides the position of the vehicle ahead stored in the position storage device (25a) if it has been determined that the positions of the own vehicle (M1) and the vehicle ahead (M2) satisfy the relationship. [5] Vehicle speed control device according to claim 4, wherein the override device (27) determines that the positions of the own vehicle (M1) and the vehicle ahead (M2) satisfy the relationship such that the detection accuracy of the following distance sensor (12) will decrease if the following distance between the own vehicle (M1) and the vehicle ahead (M2) is greater than a predetermined distance. [6] Vehicle speed control device according to claim 4 or 5, wherein, when the vehicle ahead (M2) has deviated from a position in front of the vehicle ahead (M1) and is now in a wide-angle range of the following distance sensor (12), the override device (27) determines that the positions of the vehicle ahead (M1) and the vehicle ahead (M2) satisfy the relationship such that the detection accuracy of the following distance sensor (12) will decrease. [7] Vehicle speed control device according to one of claims 4 to 6, wherein, when a relative speed between the vehicle ahead (M2) and the vehicle ahead (M1) is large, the override device (27) determines that the positions of the vehicle ahead (M1) and the vehicle ahead (M2) satisfy the relationship such that the detection accuracy of the following distance sensor (12) will decrease. [8] Vehicle speed control device according to any one of claims 2 to 7, wherein The position update device (25c) updates each advance vehicle position stored in the position storage device (25a) as the previous value each time the path of motion of the advance vehicle (M2) is calculated, when the override device (27) determines that neither the own vehicle (M1) nor the advance vehicle (M2) will deviate from the current course and the advance vehicle position stored in the position storage device (25a) is in effect, and the position update device (25c) performs the coordinate transformation of the advance vehicle position stored in the position storage device (25a) on the basis of the speed and yaw rate of the own vehicle (M1) and updates the value of the advance vehicle position after the coordinate transformation as the previous value. [9] Vehicle speed control method (10) for controlling the movement of one's own vehicle (M1) on the basis of a predicted course which is a future course of the own vehicle (M1), comprising: a step (25a) of chronologically storing a forward vehicle position, which is a position of a forward vehicle (M2) moving in front of the own vehicle (M1), in a position storage device (25a); a step (21) of calculating the predicted course based on a motion path of the advance vehicle position stored in the position memory device (25a); and a step of updating (25c) each value stored in the position memory device (25a) each time a motion path of the preceding vehicle (M2) is calculated, wherein The update step involves receiving a radius of curvature (R) of a road on which the own vehicle (M1) is moving, wherein the radius of curvature (R) is estimated on the basis of a speed and a yaw rate of the own vehicle (M1), performing a coordinate transformation of the advance vehicle position stored in the position storage device (25a) on the basis of the received radius of curvature (R), and updating the value of the advance vehicle position after the coordinate transformation as the previous value. [10] Vehicle speed control program for controlling the movement of one's own vehicle (M1) on the basis of a predicted course which is a future course of the own vehicle (M1), wherein the program causes a computer to execute: a position storage step of the chronological storage of a forward vehicle position, which is a position of a forward vehicle (M2) moving in front of the own vehicle (M1), in a position storage device (25a); a course calculation step of calculating the predicted course based on a motion path of the advance vehicle position stored in the position memory device (25a); and an update step of updating each value stored in the position memory device (25a) each time a motion path of the preceding vehicle (M2) is calculated, wherein The update step receives a radius of curvature (R) of a road on which the own vehicle (M1) is moving, wherein the radius of curvature (R) is estimated on the basis of a speed and a yaw rate of the own vehicle (M1), performs a coordinate transformation of the advance vehicle position stored in the position storage device (25a) on the basis of the received radius of curvature (R), and updates the value of the advance vehicle position after the coordinate transformation as the previous value.

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