JP2019023021A - Vehicle travel control device - Google Patents

Abstract

To provide a vehicle travel control device which executes constant speed control (CC) that constantly travels an own vehicle according to a target speed or a following inter-vehicle distance control (ACC) that makes the own vehicle travel so as to follow a preceding vehicle while keeping an inter-vehicle distance between the own vehicle and the preceding vehicle at a predetermined distance.SOLUTION: A vehicle travel control device calculates a first target acceleration (G1) based on road information acquired from a navigation device, and calculates a second target acceleration (G2) based on a radius (R2) of curvature of a road on which an own vehicle currently travels. The vehicle travel control device determines a set target acceleration (Gf) from the first target acceleration and the second target acceleration according to the current state of the device. The vehicle travel control device determines the set target acceleration as a final target acceleration, when the set target acceleration is smaller than an acceleration for constant speed control or an acceleration (Gtgt) for following inter-vehicle distance control.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a vehicle travel control device that controls the speed (ie, vehicle speed) of a vehicle when traveling on a curved road (hereinafter simply referred to as “curve”).

  Conventionally, a vehicle traveling control device (hereinafter referred to as “conventional device”) that detects a curve ahead of the vehicle and accelerates or decelerates the vehicle according to the detected curve has been proposed (for example, Patent Document 1). See).

JP 2010-149700 A

  The conventional device searches for road information ahead of the vehicle using a navigation device mounted on the vehicle, and calculates a curvature radius (turning radius) of a curve ahead of the vehicle based on the road information. And a conventional apparatus performs the deceleration control which decelerates a vehicle based on the calculated turning radius. However, the conventional device, for example, may be referred to simply as “navigation device failure” (hereinafter collectively referred to as “navigation device failure”), for example, positioning error of the navigation device, deficiency of map information, and communication abnormality with the navigation device. .) Is not designed in consideration of the occurrence.

  For example, in a branch road that is divided into a straight road and a curve, the navigation device may cause the vehicle to move on the other straight line of the branch road due to the above positioning error even though the vehicle is traveling on one curve of the branch road. It may be determined that the vehicle is traveling on a road. In this case, the conventional device receives the information on the straight road from the navigation device, and therefore does not perform deceleration control of the vehicle.

  Furthermore, in a situation where there is a curve in front of the vehicle, the conventional device may not be able to acquire road information ahead of the vehicle from the navigation device due to a communication error with the navigation device. However, since the conventional apparatus does not perform an appropriate process for a case where road information ahead of the vehicle cannot be acquired, the vehicle cannot perform deceleration control until the vehicle reaches a curve ahead.

  The present invention has been made to solve the above problems. That is, one of the objects of the present invention is vehicle travel that can appropriately control the vehicle speed until the vehicle reaches a curve ahead or when the vehicle travels a curve in the event of a malfunction of the navigation device. It is to provide a control device.

The vehicle travel control device of the present invention (hereinafter sometimes referred to as “the device of the present invention”)
Constant speed control that causes the host vehicle to travel at a constant speed according to a target speed, and the following inter-vehicle distance that causes the host vehicle to follow the preceding vehicle while maintaining a predetermined distance between the host vehicle and the preceding vehicle. Vehicle control means (206) for executing at least one of control,
Information acquisition means (201) for receiving road information regarding the position of the host vehicle and the road ahead of the host vehicle from the navigation device (20, 21, 22, 23) mounted on the host vehicle;
Detection means (15, 18) for detecting traveling state information (SPD, YRa) representing the current traveling state of the host vehicle;
When the host vehicle reaches the predetermined section so that the lateral acceleration of the host vehicle is not more than a predetermined allowable lateral acceleration when the host vehicle travels on a predetermined section of the road ahead of the host vehicle. First target acceleration calculating means (202) for calculating a first target acceleration (G1), which is a target value of acceleration for decelerating the vehicle, based on the road information and the running state information;
A radius of curvature estimation means (203) for estimating a radius of curvature (R2) of a road on which the host vehicle is currently traveling based on the traveling state information;
A second target acceleration (G2), which is a target value of acceleration for decelerating the host vehicle so that the lateral acceleration of the host vehicle becomes equal to or less than the allowable lateral acceleration after a predetermined time, is set to the estimated radius of curvature and Second target acceleration calculating means (204) for calculating based on the running state information;
When the information acquisition means has successfully acquired the road information from the navigation device, it is determined that the current device state is a normal state (402), and the information acquisition means obtains the road information from the navigation device. State determination means (207) for determining that the current device state is a fail state (403) when not successfully acquired;
Target acceleration selection means (205) for determining a set target acceleration (Gf) according to the current device state determined by the state determination means;
With
The vehicle control means includes
When executing the constant speed control, a constant speed control acceleration (CC control target acceleration) that is a target value of acceleration for accelerating or decelerating the host vehicle so that the speed of the host vehicle matches the target speed. Gtgt) is determined as the third target acceleration (510),
When executing the following inter-vehicle distance control, the following inter-vehicle distance is a target value of acceleration for accelerating or decelerating the own vehicle so that the inter-vehicle distance between the own vehicle and the preceding vehicle is maintained at the predetermined distance. A distance control acceleration (ACC control target acceleration Gtgt) is determined as the third target acceleration (510);
The target acceleration selecting means is
When the current device state is the normal state, the smaller one of the first target acceleration and the second target acceleration is determined as the set target acceleration (550),
When the current device state is the fail state, the second target acceleration is determined as the set target acceleration (555);
The vehicle control means includes
When the set target acceleration is smaller than the third target acceleration, the speed of the host vehicle is controlled by controlling the acceleration of the host vehicle so that the actual acceleration of the host vehicle matches the set target acceleration. (560: Yes, 565),
When the third target acceleration is less than or equal to the set target acceleration, the speed of the host vehicle is controlled by controlling the acceleration of the host vehicle so that the actual acceleration of the host vehicle matches the third target acceleration. (560: No, 570).

  The device according to the present invention can control the vehicle speed until the own vehicle reaches a curve ahead or when the own vehicle is traveling on the curve in the event of a malfunction of the navigation device. For example, on a branch road that is divided into a straight road and a curve, the information acquisition means erroneously outputs information on the straight road due to a positioning error of the navigation device even though the host vehicle is actually driving a curve. Suppose you received it. In this case, the first target acceleration calculated based on the straight road information is larger than the second target acceleration calculated based on the curvature radius of the currently traveling curve. At this time, the target acceleration selecting means selects the smaller second target acceleration as the set target acceleration. When the second target acceleration is smaller than the third target acceleration (constant speed control acceleration or following inter-vehicle distance control acceleration), the vehicle control means can decelerate the vehicle using the second target acceleration. Therefore, even when the information acquisition means receives incorrect road information, the vehicle control means can perform deceleration control using the second target acceleration calculated based on the curvature radius of the currently traveling curve.

  Furthermore, when the information acquisition unit cannot normally acquire the road information from the navigation device, that is, when the current device state is a failure state, the target acceleration selection unit determines the second target acceleration as the set target acceleration. Therefore, even when the current device state is a failure state, if the second target acceleration is smaller than the third target acceleration (constant speed control acceleration or tracking inter-vehicle distance control acceleration), the vehicle control means The vehicle can be decelerated using the second target acceleration calculated based on the radius of curvature of the currently traveling curve.

  In the above description, in order to help understanding of the present invention, names and / or symbols used in the embodiment are attached to the configuration of the invention corresponding to the embodiment described later in parentheses. However, each component of the present invention is not limited to the embodiment defined by the reference numerals.

1 is a schematic configuration diagram of a vehicle travel control device according to an embodiment of the present invention. FIG. 2 is a functional block diagram of a driving assistance ECU shown in FIG. 1. It is the top view which showed the curvature radius of the vehicle and the curve. It is a state transition diagram of the system state which concerns on embodiment of this invention. 2 is a flowchart for explaining the operation of the driving assistance ECU shown in FIG. 1.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

  As shown in FIG. 1, a vehicle travel control device according to an embodiment of the present invention (hereinafter, may be referred to as “the present implementation device”) is a vehicle (hereinafter referred to as another vehicle). The driving support ECU 10, the navigation ECU 20, the engine ECU 30, and the brake ECU 40 are provided.

  These ECUs are electric control units (Electric Control Units) each including a microcomputer as a main part, and are connected to each other so as to be able to transmit and receive information via a CAN (Controller Area Network) (not shown). In this specification, the microcomputer includes a CPU 101, a ROM 102, a RAM 103, an interface (I / F) 104, and the like. The CPU 101 implements various functions by executing instructions (programs, routines) stored in the ROM 102.

  The driving assistance ECU 10 is connected to sensors (including switches) listed below, and receives detection signals or output signals from these sensors. Each sensor may be connected to an ECU other than the driving support ECU 10. In that case, the driving assistance ECU 10 receives a detection signal or an output signal of the sensor via the CAN from the ECU to which the sensor is connected.

The accelerator pedal operation amount sensor 11 detects an operation amount (accelerator opening) of the accelerator pedal 11a of the host vehicle and outputs a signal representing the accelerator pedal operation amount AP.
The brake pedal operation amount sensor 12 detects the operation amount of the brake pedal 12a of the host vehicle and outputs a signal representing the brake pedal operation amount BP.

The steering angle sensor 13 detects the steering angle of the host vehicle and outputs a signal representing the actual steering angle θ.
The steering torque sensor 14 detects the steering torque applied to the steering shaft US of the host vehicle by operating the steering handle SW, and outputs a signal representing the actual steering torque Tra.
The vehicle speed sensor 15 detects the traveling speed (vehicle speed) of the host vehicle and outputs a signal representing the vehicle speed SPD.

  The ambient sensor 16 is configured to acquire information on at least a road ahead of the host vehicle and a three-dimensional object existing on the road. The three-dimensional object represents, for example, a moving object such as a pedestrian, a bicycle, and a car, and a fixed object such as a utility pole, a tree, and a guardrail. Hereinafter, these three-dimensional objects may be referred to as “targets”. Further, the ambient sensor 16 calculates the presence / absence of the target and the relative relationship between the host vehicle and the target (that is, the distance between the host vehicle and the target, the relative speed between the host vehicle and the target, etc.). It is designed to output.

  The ambient sensor 16 includes, for example, a radar sensor and a camera sensor.

  The radar sensor, for example, emits a radio wave in the millimeter wave band (hereinafter referred to as “millimeter wave”) to the surrounding area of the own vehicle including at least the front area of the own vehicle, and by a target existing within the emission range. A reflected millimeter wave (ie, a reflected wave) is received.

  More specifically, the radar sensor includes a millimeter wave transmission / reception unit and a processing unit. The processing unit has a phase difference between the millimeter wave transmitted from the millimeter wave transmitting / receiving unit and the reflected wave received by the millimeter wave transmitting / receiving unit, the attenuation level of the reflected wave, and the time from when the millimeter wave is transmitted until the reflected wave is received. Based on the above, for each detected target (n), an inter-vehicle distance (vertical distance) Dfx (n), a relative speed Vfx (n), a lateral distance Dfy (n), a relative lateral speed Vfy (n), etc. are predetermined. Get every time.

The inter-vehicle distance Dfx (n) is a distance along the central axis of the host vehicle between the host vehicle and the target (n) (for example, a preceding vehicle).
The relative speed Vfx (n) is a difference (= Vs−Vj) between the speed Vs of the target (n) (for example, the preceding vehicle) and the speed Vj of the host vehicle. The speed Vs of the target (n) is the speed of the target (n) in the traveling direction of the host vehicle.
The lateral distance Dfy (n) is a distance from the central axis in the direction orthogonal to the central axis of the host vehicle of the “center position of the target (n) (for example, the vehicle width center position of the preceding vehicle)”. The lateral distance Dfy (n) is also referred to as “lateral position”.
The relative lateral speed Vfy (n) is a speed in a direction orthogonal to the center axis of the host vehicle at the center position of the target (n) (for example, the vehicle width center position of the preceding vehicle).

  The camera sensor includes a stereo camera and an image processing unit. The stereo camera captures a landscape of a left area and a right area in front of the vehicle and acquires a pair of left and right image data. The image processing unit calculates and outputs the presence / absence of the target and the relative relationship between the vehicle and the target based on a pair of left and right image data captured by the stereo camera. In this case, the driving assistance ECU 10 synthesizes the relative relationship between the host vehicle and the target obtained by the radar sensor and the relative relationship between the host vehicle and the target obtained by the camera sensor. The relative relationship between the target and the target is determined. Furthermore, the camera sensor recognizes lane markers such as white lines on the left and right of the road (hereinafter simply referred to as “white lines”) based on the captured pair of left and right image data, and shapes of the road (for example, , Curvature radius) and the positional relationship between the road and the vehicle are calculated and output.

  Information acquired by the ambient sensor 16 is referred to as target information. The ambient sensor 16 repeatedly transmits target information to the driving assistance ECU 10 every time a predetermined time elapses. Note that the ambient sensor 16 does not necessarily include both the radar sensor and the camera sensor, and may include, for example, only the radar sensor or only the camera sensor.

  The operation switch 17 is a switch operated by the driver. The driver can select whether or not to execute follow-up inter-vehicle distance control (ACC: adaptive cruise control) by operating the operation switch 17.

  The yaw rate sensor 18 detects the yaw rate of the host vehicle and outputs an actual yaw rate YRa.

  Hereinafter, information representing the current traveling state of the vehicle, such as the vehicle speed SPD, the actual yaw rate YRa, the actual steering angle θ, and the actual steering torque Tra may be referred to as “traveling state information”.

  The driving assistance ECU 10 can perform follow-up inter-vehicle distance control (ACC). Further, the driving support ECU 10 can execute speed adjustment support control (hereinafter also referred to as “speed management control”). Speed adjustment support control is travel control that controls the speed of the host vehicle based on the radius of curvature of the curve ahead of the host vehicle. As will be described later, the driving assistance ECU 10 includes a target acceleration for ACC control (including a target acceleration for constant speed control, which will be described later, and “third target acceleration” for convenience in a period during which the host vehicle travels on a road including a curve section. And a target acceleration for speed adjustment support control are selected. The driving assistance ECU 10 controls the vehicle speed of the host vehicle by adjusting the acceleration of the host vehicle so that the acceleration of the host vehicle matches the selected target acceleration.

  The vehicle is equipped with a navigation device. The navigation device includes a navigation ECU 20. The navigation ECU 20 performs route guidance of the host vehicle based on the position of the host vehicle and map information. For this purpose, the navigation ECU 20 is connected to a GPS receiver 21 that receives a GPS signal for detecting the position of the host vehicle, a map database 22 that stores map information, and a touch panel display 23 that is a human machine interface. Has been. The navigation ECU 20 specifies the current position (current position) Pnow of the host vehicle based on the GPS signal, and performs various arithmetic processes based on the position Pnow of the host vehicle and the map information stored in the map database 22. The route guidance is performed using the display 23.

  The map information stored in the map database 22 includes road information. The road information includes road parameters in each road section. For example, on the road information, the width of the road, the gradient, the single gradient (kant), the radius of curvature (or the curvature), and the like are associated with each of the road sections. The curvature radius of the road is, for example, a curvature radius of a curve drawn by a center line connecting the center in the width direction of the traveling road (see FIG. 3). The curvature is the reciprocal of the radius of curvature.

  The engine ECU 30 is connected to the engine actuator 31. The engine actuator 31 includes a gasoline fuel injection / spark ignition / throttle valve actuator that changes the opening of the throttle valve of the internal combustion engine 32. The engine ECU 30 can change the torque generated by the internal combustion engine 32 by driving the engine actuator 31. Torque generated by the internal combustion engine 32 is transmitted to drive wheels (not shown) via a transmission (not shown). Therefore, the engine ECU 30 can control the driving force of the host vehicle and change the acceleration state (acceleration) by controlling the engine actuator 31.

  The brake ECU 40 is connected to the brake actuator 41. The brake actuator 41 is provided in a hydraulic circuit between a master cylinder (not shown) that pressurizes hydraulic oil by the depression force of the brake pedal 12a and a friction brake mechanism 42 provided on the left and right front and rear wheels. The brake actuator 41 adjusts the hydraulic pressure supplied to the wheel cylinder built in the brake caliper 42 b of the friction brake mechanism 42 in accordance with an instruction from the brake ECU 40. When the wheel cylinder is actuated by the hydraulic pressure, the brake pad is pressed against the brake disc 42a and a friction braking force is generated. Accordingly, the brake ECU 40 can change the acceleration state (deceleration, that is, negative acceleration) by controlling the braking force of the host vehicle by controlling the brake actuator 41.

  Next, the operation of the present embodiment configured as described above will be described. As described above, the driving assistance ECU 10 executes the following inter-vehicle distance control and the speed adjustment assistance control. First, these controls will be described.

(Tracking inter-vehicle distance control)
Following inter-vehicle distance control (ACC) is driving support control in which an inter-vehicle control function is added to constant speed control (referred to as cruise control: CC). Constant speed control (CC) is control that causes the host vehicle to travel at a constant speed according to a target vehicle speed without requiring an accelerator pedal operation by the driver. The inter-vehicle distance control function is a function that causes the host vehicle to follow the preceding vehicle while maintaining a predetermined distance between the host vehicle and the preceding vehicle that is traveling immediately before the host vehicle. The following inter-vehicle distance control itself is well known (see, for example, Japanese Patent Application Laid-Open No. 2014-148293, Japanese Patent Application Laid-Open No. 2006-315491, Japanese Patent No. 4172434, and Japanese Patent No. 4929777). Accordingly, a brief description will be given below.

  The driving assistance ECU 10 executes the following inter-vehicle distance control when the following inter-vehicle distance control is requested by the operation of the operation switch 17.

  More specifically, the driving assistance ECU 10 selects the tracking target vehicle based on the target information acquired by the surrounding sensor 16 when the tracking inter-vehicle distance control is required. For example, the driving assistance ECU 10 determines that the relative position of the target (n) specified from the detected lateral distance Dfy (n) and inter-vehicle distance Dfx (n) of the target (n) increases as the inter-vehicle distance increases. It is determined whether or not the vehicle exists within a predetermined tracking target vehicle area so that the size of the vehicle is small. When the relative position of the target exists in the tracking target vehicle area for a predetermined time or more, the driving assistance ECU 10 selects the target (n) as the tracking target vehicle (a). Note that, when there are a plurality of tracking target vehicles, the driving support ECU 10 selects a vehicle having the smallest inter-vehicle distance Dfx (n) as the tracking target vehicle from among them.

  Further, the driving assistance ECU 10 calculates the target acceleration Gtgt according to either of the following formulas (1) and (2). The target acceleration Gtgt calculated according to either the expression (1) or the expression (2) is also referred to as “following inter-vehicle distance control (ACC control) target acceleration Gtgt”. In equations (1) and (2), Vfx (a) is the relative speed of the vehicle to be followed (a), and k1 and k2 are predetermined positive gains (coefficients). ΔD1 is an inter-vehicle deviation (= Dfx (a) −Dtgt) obtained by subtracting the target inter-vehicle distance Dtgt from the inter-vehicle distance Dfx (a) of the tracking target vehicle (a). The target inter-vehicle distance Dtgt is calculated by multiplying the target inter-vehicle time Ttgt set by the driver using the operation switch 17 by the vehicle speed SPD of the own vehicle (that is, Dtgt = Ttgt · SPD).

When the value (k1 · ΔD1 + k2 · Vfx (a)) is positive or “0”, the driving assistance ECU 10 determines the target acceleration Gtgt using the following equation (1). ka1 is a positive gain (coefficient) for acceleration, and is set to a value of “1” or less.
When the value (k1 · ΔD1 + k2 · Vfx (a)) is negative, the driving assistance ECU 10 determines the target acceleration Gtgt using the following equation (2). kd1 is a gain (coefficient) for deceleration, and is set to “1” in this example.
Gtgt (for acceleration) = ka1 · (k1 · ΔD1 + k2 · Vfx (a)) (1)
Gtgt (for deceleration) = kd1 · (k1 · ΔD1 + k2 · Vfx (a)) (2)

  In addition, when the target does not exist in the tracking target vehicle area, the driving assistance ECU 10 executes constant speed control (CC). That is, the driving assistance ECU 10 determines the target acceleration Gtgt based on the target vehicle speed and the vehicle speed SPD so that the vehicle speed SPD of the host vehicle matches the target vehicle speed set by the operation of the operation switch 17. The driving assistance ECU 10 sets the target acceleration Gtgt to “0” if the target vehicle speed matches the vehicle speed SPD. When the target vehicle speed is higher than the vehicle speed SPD, the driving assistance ECU 10 gradually increases the target acceleration Gtgt. The driving assistance ECU 10 gradually decreases the target acceleration Gtgt when the target vehicle speed is lower than the vehicle speed SPD. The target acceleration Gtgt calculated in this way is also referred to as “constant speed control (CC control) target acceleration Gtgt”.

  The driving assistance ECU 10 controls the engine actuator 31 using the engine ECU 30 and the brake actuator 41 using the brake ECU 40 as necessary so that the vehicle acceleration matches the target acceleration Gtgt.

(Speed adjustment support control)
Next, speed adjustment support control will be described. As shown in FIG. 2, the driving assistance ECU 10 includes a road information acquisition unit 201, a first target acceleration calculation unit 202, a curvature radius estimation unit 203, as functional components for executing the speed adjustment support control. , A second target acceleration calculation unit 204, a target acceleration selection unit 205, a vehicle control unit 206, and a system state determination unit 207. These execute the processing (calculation) described below every time a predetermined time elapses.

  The road information acquisition unit 201 acquires road information related to the current position of the host vehicle and a road ahead of the current position of the host vehicle. More specifically, the road information acquisition unit 201 acquires the road information included in the map information of the position Pnow of the host vehicle and the map database 22 via the navigation ECU 20. For example, the road information includes information on various parameters of a section constituting a position from the position Pnow of the host vehicle to a point 400 m ahead of the host vehicle. The road information acquisition unit 201 includes information on “curvature radius R (for example, R1 in FIG. 3), superelevation i (kant) and position of the start point of the section” as various parameters of each section, and Information on the position Pnow of the vehicle is output to the first target acceleration calculation unit 202. The road information acquisition unit 201 outputs information on the single gradient inow of the position Pnow of the host vehicle to the second target acceleration calculation unit 204.

The first target acceleration calculation unit 202 calculates a first target acceleration G1 in which the lateral acceleration of the host vehicle is suppressed to a predetermined allowable lateral acceleration (for example, 0.15 g) or less in all the above sections. Specifically, in order to calculate the first target acceleration G1, the first target acceleration calculation unit 202 first calculates the target vehicle speed V1 according to the following equation (3) for each of the above sections.
Target vehicle speed V1 = {R × (Mg + g × i)} ^1/2 (3)
R: radius of curvature [m]
Mg: Allowable lateral acceleration [m / s ² ]
g: Gravitational acceleration≈9.8 [m / s ² ]
i: Super gradient [%]

  The first target acceleration calculation unit 202 calculates a distance L from the position Pnow of the host vehicle to the position of each start point of the above section. Further, the first target acceleration calculation unit 202 acquires information on the current vehicle speed SPD from the vehicle speed sensor 15. The first target acceleration calculation unit 202 calculates the target acceleration for each of the above sections based on the target vehicle speed V1, the current vehicle speed SPD, and the distance L. The target acceleration is an acceleration (deceleration) necessary for the vehicle speed of the host vehicle when the host vehicle reaches the start point of each of the above sections to coincide with the target vehicle speed V1.

  In the present specification, the acceleration includes acceleration during acceleration (positive value acceleration) and acceleration during deceleration (negative value acceleration). The first target acceleration calculating unit 202 determines the minimum acceleration as the first target acceleration G1 from among the target accelerations of the respective sections. Therefore, the first target acceleration G1 is an acceleration at which the lateral acceleration of the host vehicle is suppressed below the allowable lateral acceleration in all of the above sections. The first target acceleration calculation unit 202 outputs the first target acceleration G1 to the target acceleration selection unit 205.

The curvature radius estimation unit 203 calculates a curvature radius R2 (see FIG. 3) of a road on which the host vehicle is currently traveling. Specifically, the curvature radius estimation unit 203 acquires information on the current vehicle speed SPD from the vehicle speed sensor 15 and acquires information on the actual yaw rate YRa from the yaw rate sensor 18. The curvature radius estimation unit 203 calculates a curvature radius R2 according to the following equation (4) based on the current vehicle speed SPD and the actual yaw rate YRa.
Curvature radius R2 = SPD / YRa (4)
The curvature radius estimation unit 203 outputs information on the curvature radius R2 to the second target acceleration calculation unit 204.

  The second target acceleration calculation unit 204 calculates a second target acceleration G2 that suppresses the lateral acceleration of the host vehicle to a predetermined allowable lateral acceleration (for example, 0.15 g) after a predetermined set time (for example, 1 second). . More specifically, the second target acceleration calculating unit 204 substitutes a predetermined allowable lateral acceleration, a curvature radius R2 and a single gradient inow of the position Pnow of the host vehicle into the right side of the above equation (3) to thereby set the target vehicle speed V2. Is calculated.

  The second target acceleration calculation unit 204 is based on the vehicle speed SPD of the host vehicle, the target vehicle speed V2, and a predetermined set time, so that the vehicle speed of the host vehicle matches the target vehicle speed V2 after the predetermined set time ( (Deceleration) is calculated as the second target acceleration G2. The second target acceleration calculation unit 204 outputs the second target acceleration G2 to the target acceleration selection unit 205.

  As shown in FIG. 4, the system state determination unit 207 determines whether the system state is any one of the control standby state 401, the normal state 402, and the failure state 403 after the driving support ECU 10 is turned on. Are repeatedly determined as described later. The system state determination unit 207 outputs information Info about the determined current system state (hereinafter simply referred to as “system state information”) to the target acceleration selection unit 205.

  When the driving assist ECU 10 is powered on, the system state determination unit 207 determines that the system state is the control standby state 401. This control standby state 401 is a state immediately after the follow-up inter-vehicle distance control is requested by the operation of the operation switch 17 (immediately after the system is turned on), and road information ahead of the host vehicle has not yet been acquired. When the system state determination unit 207 determines that the system state is in the control standby state 401, the system state determination unit 207 repeatedly determines whether or not a predetermined normal condition is satisfied each time a predetermined time elapses. For example, the predetermined normal condition is that when a predetermined number of road parameters (information including curvature radius R, superelevation i and position of the start point of the section) for a predetermined number of sections in front of the host vehicle can be acquired normally. To establish. When the road information acquisition unit 201 has successfully acquired road parameters for a predetermined number of sections ahead of the host vehicle, the road information acquisition unit 201 indicates a signal Nsig (hereinafter referred to as “normal signal”) indicating that the road parameters have been normally acquired. Is output to the system state determination unit 207. When the system state determination unit 207 receives the normal signal Nsig from the road information acquisition unit 201, the system state determination unit 207 determines that a predetermined normal condition is satisfied, and determines that the system state has transitioned from the control standby state 401 to the normal state 402.

The normal state 402 is a state in which the road parameters for the predetermined number of sections can be normally acquired. When the system state determination unit 207 determines that the system state is in the normal state 402, the system state determination unit 207 repeatedly determines whether or not a predetermined failure condition is satisfied every time a predetermined time elapses. For example, the predetermined failure condition is satisfied when at least one of (a) to (d) is satisfied.
(A) An abnormality has occurred in the navigation ECU 20.
(B) An abnormality has occurred in communication with the navigation ECU 20.
(C) The acquired road parameter in front of the vehicle includes an abnormal value or is missing.
(D) The road parameters have changed compared to the last time.

  With respect to the condition (a), the navigation ECU 20 monitors whether or not an abnormality has occurred in the navigation ECU 20, and when any abnormality has occurred, the navigation ECU 20 indicates that the navigation device has failed. Fsig (hereinafter referred to as “fail signal”) is output to the system state determination unit 207.

  With respect to the condition (b), the road information acquisition unit 201 measures the time from the start of communication with the navigation ECU 20 until the road parameters are received. When the road information acquisition unit 201 cannot receive road parameters from the navigation ECU 20 for a predetermined abnormality determination time or longer, the road information acquisition unit 201 outputs a fail signal Fsig to the system state determination unit 207.

  Regarding the condition (c), the road information acquisition unit 201 determines whether the road information received from the navigation ECU 20 includes predetermined parameters (the radius of curvature R, the super gradient i, and the position of the start point of each section). To do. Further, when a predetermined parameter is included in the road information, the road information acquisition unit 201 determines whether each value of the parameter is within a predetermined normal range set for each parameter type. The road information acquisition unit 201 outputs a fail signal Fsig to the system state determination unit 207 when a predetermined parameter is not included in the road information or when the parameter value is outside the normal range.

  With respect to the condition (d), the road information acquisition unit 201 records in the RAM 103 a road information parameter (hereinafter simply referred to as “previous parameter”) for a predetermined section acquired at the previous calculation timing. The previous parameter is compared with the parameter of the road information of the corresponding section acquired at the current calculation timing (hereinafter simply referred to as “current parameter”). If the current parameter is different from the previous parameter, the navigation ECU 20 outputs a road parameter that is different from the road determined by the navigation ECU 20 that the host vehicle is traveling at the previous calculation timing due to a positioning error in the navigation device. There is a possibility that. Therefore, the road information acquisition unit 201 outputs the fail signal Fsig to the system state determination unit 207 when the current parameter is different from the previous parameter.

  When receiving the fail signal Fsig, the system state determination unit 207 determines that a predetermined failure condition is satisfied, and determines that the system state has transitioned from the normal state 402 to the fail state 403.

  The fail state 403 is a state in which road parameters for the predetermined number of sections are not normally acquired. When the system state determination unit 207 determines that the system state is in the fail state 403, the system state determination unit 207 repeatedly determines whether or not a predetermined recovery condition is satisfied each time a predetermined time elapses. The predetermined recovery condition is satisfied when the road parameters for the predetermined number of sections can be normally acquired. For example, the predetermined recovery condition is satisfied when the communication abnormality between the road information acquisition unit 201 and the navigation ECU 20 is resolved and the road information acquisition unit 201 can normally acquire the parameters of the road ahead of the host vehicle. The road information acquisition unit 201 outputs a normal signal Nsig to the system state determination unit 207 when the road parameters for a predetermined number of sections ahead of the host vehicle can be normally acquired. When receiving the normal signal Nsig, the system state determination unit 207 determines that a predetermined recovery condition is satisfied, and determines that the system state has transitioned from the fail state 403 to the normal state 402.

Further, in the fail state 403, the system state determination unit 207 repeatedly determines whether or not a predetermined standby condition is satisfied every time a predetermined time elapses. For example, the predetermined standby condition is satisfied when the following expression (5) is satisfied. The second target acceleration calculation unit 204 records the second target acceleration G2 in the RAM 103 every time the second target acceleration G2 is calculated. The target acceleration calculation unit 206 a records the target acceleration Gtgt in the RAM 103 every time the target acceleration Gtgt is calculated. The system state determination unit 207 determines whether the second target acceleration G2 and the target acceleration Gtgt recorded in the RAM 103, that is, the latest second target acceleration G2 and the target acceleration Gtgt satisfy the following expression (5). When the following equation (5) is satisfied, the system state determination unit 207 determines that the system state has transitioned from the fail state 403 to the control standby state 401.
Target acceleration Gtgt <second target acceleration G2 (5)

  The standby condition is a condition for determining whether or not the second target acceleration G2 is continuously used as the set target acceleration Gf for speed adjustment support control in the fail state 403. As will be described later with reference to FIG. 5, in the present embodiment, when the current system state is the fail state 403, the target acceleration selection unit 205 determines the second target acceleration G2 as the set target acceleration Gf. In the fail state 403, if the target acceleration Gtgt for ACC is smaller than the second target acceleration G2, the vehicle speed may be controlled by ACC without performing the speed adjustment support control. Therefore, when the predetermined standby condition is satisfied, the system state determination unit 207 causes the system state to transition from the fail state 403 to the control standby state 401 so that the target acceleration Gtgt for ACC is selected.

  The target acceleration selection unit 205 acquires system state information Sinfo from the system state determination unit 207. The target acceleration selection unit 205 determines a set target acceleration Gf for speed adjustment support control as described later according to the current system state. The target acceleration selection unit 205 outputs the determined set target acceleration Gf to the vehicle control unit 206.

  The vehicle control unit 206 selects and executes either of the following inter-vehicle distance control (ACC) or the speed adjustment support control. More specifically, the vehicle control unit 206 includes a target acceleration calculation unit 206a. When the following vehicle distance control is required, the target acceleration calculation unit 206a, when there is a vehicle to be followed (a), the target acceleration Gtgt for ACC control according to either the above equation (1) or (2). Is calculated every time a predetermined time elapses. The target acceleration calculation unit 206a calculates the CC control target acceleration Gtgt for making the vehicle speed SPD coincide with the target vehicle speed when the following vehicle distance control is requested and the tracking target vehicle (a) does not exist. . Hereinafter, the ACC control target acceleration Gtgt and the CC control target acceleration Gtgt are also referred to as “ACC / CC control target acceleration Gtgt (third target acceleration)”.

  Further, the vehicle control unit 206 compares the target acceleration Gtgt for ACC / CC control with the set target acceleration Gf for speed adjustment support control. When the set target acceleration Gf is smaller than the target acceleration Gtgt for ACC / CC control, the vehicle control unit 206 selects the set target acceleration Gf as the final target acceleration Ge. On the other hand, when the target acceleration Gtgt for ACC / CC control is equal to or less than the set target acceleration Gf, the vehicle control unit 206 selects the target acceleration Gtgt as the final target acceleration Ge. The vehicle control unit 206 calculates the amount of change per unit time of the vehicle speed SPD as the actual acceleration. The vehicle control unit 206 controls the engine actuator 31 using the engine ECU 30 so that the actual acceleration matches the final target acceleration Ge (that is, the selected target acceleration Gf or Gtgt), and as necessary. The brake actuator 41 is controlled using the brake ECU 40.

(Specific control)
Next, a specific operation of the driving assistance ECU 10 will be described with reference to FIG. A CPU 101 (hereinafter simply referred to as “CPU”) of the driving assistance ECU 10 executes a “travel control routine” shown in the flowchart of FIG. 5 every time a predetermined time elapses. Further, the CPU specifies the system state as described above by executing a routine (not shown).

Therefore, when the predetermined timing comes, the CPU starts processing from step 500 in FIG. 5 and proceeds to step 505 to determine whether or not the ACC execution condition is satisfied. The ACC execution condition is a condition that is satisfied when both condition 1 and condition 2 described below are satisfied.
(Condition 1) Follow-up inter-vehicle distance control is requested by operating the operation switch 17.
(Condition 2) The vehicle speed SPD is not less than the low-side vehicle speed threshold value SPD1 and less than the high-side vehicle speed threshold value SPD2.

  If the ACC execution condition is not satisfied, the CPU makes a “No” determination at step 505 to proceed to step 595 to end the present routine tentatively. On the other hand, if the ACC execution condition is satisfied, the CPU makes a “Yes” determination at step 505 to sequentially perform the processing from step 510 to step 530 described below, and then proceeds to step 540.

  Step 510: The CPU calculates the target acceleration Gtgt for ACC / CC control as described above. This step corresponds to the target acceleration calculation unit 206a of the vehicle control unit 206.

  Step 515: The CPU, via the navigation ECU 20, provides road information (curvature radius R, superelevation i, and start point of each section) corresponding to the current position Pnow of the host vehicle and a predetermined number of sections ahead of the host vehicle. Position). This step corresponds to the road information acquisition unit 201.

  Step 520: As described above, the CPU sets the first target in which the lateral acceleration of the host vehicle is suppressed to “predetermined allowable lateral acceleration (for example, 0.15 g)” in all of the predetermined number of sections. The acceleration G1 is calculated. This step corresponds to the first target acceleration calculation unit 202.

  Step 525: As described above, the CPU estimates the curvature radius R2 of the road on which the host vehicle is currently traveling based on the current vehicle speed SPD and the actual yaw rate YRa. This step corresponds to the curvature radius estimation unit 203.

  Step 530: As described above, the CPU sets the second target acceleration at which the lateral acceleration of the host vehicle is suppressed to “predetermined allowable lateral acceleration (for example, 0.15 g)” after a predetermined set time (for example, 1 second). G2 is calculated. This step corresponds to the second target acceleration calculation unit 204.

  After executing the processing of step 530, the CPU proceeds to step 540 to acquire the current system state that has been separately determined (specified). The CPU determines whether the current system state is the control standby state 401, the normal state 402, or the fail state 403.

When the current system state is the control standby state 401, the CPU proceeds from step 540 to step 545 to set a predetermined fixed value (for example, 5 m / s ² ) as the set target acceleration Gf for convenience. The control standby state 401 is a state in which road information ahead of the host vehicle has not yet been acquired. Therefore, in such a state, it is desirable to control the vehicle speed using the target acceleration Gtgt for ACC / CC control. For this reason, the predetermined fixed value is sufficiently larger than the value that can always be determined as “No” in step 560 described later, that is, the maximum value that the target acceleration Gtgt for ACC / CC control can take. It is set to a large value.

  On the other hand, when the current system state is the normal state 402, the CPU proceeds from step 540 to step 550, and the smaller one of the first target acceleration G1 and the second target acceleration G2 is set as the set target acceleration for speed adjustment support control. Determine as Gf.

  On the other hand, if the current system state is the fail state 403, the CPU proceeds from step 540 to step 555 to determine the second target acceleration G2 as the set target acceleration Gf. The fail state 403 means that the CPU cannot acquire the correct first target acceleration G1 because the navigation device has a malfunction. Therefore, the CPU determines the second target acceleration G2 as the set target acceleration Gf as it is without comparing the first target acceleration G1 and the second target acceleration G2.

  The CPU proceeds to step 560 after executing any one of steps 545, 550, and 555. Steps 540 to 555 correspond to the target acceleration selection unit 205.

  Next, the CPU proceeds to step 560 to determine whether or not “set target acceleration Gf for speed adjustment support control” is smaller than “target acceleration Gtgt for ACC / CC control”.

  When the set target acceleration Gf is smaller than the target acceleration Gtgt, the CPU makes a “Yes” determination at step 560 to proceed to step 565 to control the vehicle speed of the host vehicle using the set target acceleration Gf (ie, speed adjustment). Support control). That is, the CPU controls the engine actuator 31 and the brake actuator 41 so that the actual acceleration of the host vehicle matches the “set target acceleration Gf as the final target acceleration Ge”. Thereafter, the CPU proceeds to step 595 to end the present routine tentatively.

  On the other hand, if the set target acceleration Gf is equal to or greater than the target acceleration Gtgt, the CPU makes a “No” determination at step 560 to proceed to step 570 to control the vehicle speed of the host vehicle using the target acceleration Gtgt (ie, , Follow-up inter-vehicle distance control including constant speed control). That is, the CPU controls the engine actuator 31 and the brake actuator 41 so that the actual acceleration of the host vehicle matches the “target acceleration Gtgt as the final target acceleration Ge”. Thereafter, the CPU proceeds to step 595 to end the present routine tentatively. Steps 560 to 570 correspond to the vehicle control unit 206.

  As described above, the present embodiment device can control the vehicle speed until the vehicle reaches a curve ahead or when the vehicle travels a curve when a problem occurs in the navigation device. For example, even if the current system state is the normal state 402, that is, even if the present implementation device can normally acquire road information from the navigation device, the present implementation device may acquire incorrect road information as follows. is there. For example, on a branch road that is divided into a straight road and a curve, the navigation device may erroneously output straight road information due to a positioning error, even though the vehicle is actually driving a curve. is there. In such a case, since the first target acceleration G1 is calculated based on the information on the straight road, the first target acceleration G1 is calculated based on the curvature radius R2 of the currently running curve. It becomes larger than G2. When the current system state is the normal state 402, the present implementation apparatus selects the smaller second target acceleration G2 of the first target acceleration G1 and the second target acceleration G2 as the set target acceleration Gf. When the second target acceleration G2 is smaller than the target acceleration Gtgt for ACC / CC control, the present embodiment can decelerate the vehicle using the second target acceleration G2. Therefore, even when the present embodiment receives information on a road different from the road on which the vehicle is actually running, the present embodiment performs deceleration control using the second target acceleration G2 calculated based on the curvature radius R2 of the currently running curve. It can be carried out.

  On the other hand, when the road parameters for the predetermined number of sections cannot be obtained from the navigation ECU 20 or when the obtained road parameters for the predetermined number of sections are not accurate, that is, the current system state is the fail state 403. In this case, the present embodiment determines the second target acceleration G2 calculated based on the curvature radius R2 of the currently running curve as the set target acceleration Gf. Therefore, even when the current system state is the fail state 403, when the second target acceleration G2 is smaller than the target acceleration Gtgt for ACC / CC control, the present embodiment uses the second target acceleration G2. The vehicle can be decelerated.

  Further, when the current system state is the control standby state 401, the present embodiment preferentially selects the target acceleration Gtgt for ACC / CC control as the final target acceleration Ge. Thereby, in the control standby state 401, this embodiment apparatus can decelerate the vehicle using the target acceleration Gtgt for ACC / CC control.

  Further, even when the current system state becomes the fail state 403, it is not necessary to perform speed adjustment support control (that is, the target acceleration Gtgt is smaller than the second target acceleration G2, and the above equation (5) is established. In this case, the present embodiment can prioritize control of the vehicle speed by ACC / CC by changing the system state from the fail state 403 to the control standby state 401. As a result, the behavior of the vehicle after the system state becomes the fail state 403 can be stabilized.

  Furthermore, the present embodiment device can select the following inter-vehicle distance control according to the situation of the host vehicle even in a situation where the host vehicle is traveling on a curve. For example, the present embodiment compares the set target acceleration Gf for speed adjustment support control with the target acceleration Gtgt for ACC control. If the target acceleration Gtgt is equal to or less than the set target acceleration Gf, the ACC control using the target acceleration Gtgt is performed. Execute. For example, it is assumed that the host vehicle catches up with a preceding vehicle while traveling on a curve, and the distance between the preceding vehicle and the preceding vehicle is smaller than a predetermined distance. In this case, a larger deceleration is required depending on the preceding vehicle factor, and it is desirable to select the target acceleration Gtgt for ACC control. In such a situation, since the target acceleration Gtgt for ACC control is smaller than the set target acceleration Gf for speed adjustment support control, the present embodiment selects the target acceleration Gtgt as the final target acceleration. Therefore, when a preceding vehicle exists while the host vehicle is traveling on a curve, safety can be improved by switching from the speed adjustment support control to the ACC control.

  As another example, when the host vehicle is traveling near the exit of a curve, the value of the curvature radius R2 gradually increases, and accordingly, the second target acceleration G2 also gradually increases. However, when the inter-vehicle distance from the preceding vehicle is small, it is necessary to suppress acceleration. In such a situation, since the target acceleration Gtgt for ACC control is smaller than the set target acceleration Gf for speed adjustment support control, the present embodiment selects the target acceleration Gtgt as the final target acceleration. Therefore, when the host vehicle is traveling near the exit of the curve and there is a preceding vehicle, the present embodiment can improve safety by switching from the speed adjustment support control to the ACC control.

  In addition, this invention is not limited to the said embodiment, A various modification can be employ | adopted within the scope of the present invention.

  The calculation method of the curvature radius R2 is not limited to the above example. For example, the value of the radius of curvature calculated based on the vehicle speed SPD and the actual yaw rate YRa may be corrected by the actual steering angle θ. Alternatively, a calculation method proposed in Japanese Patent Application Laid-Open No. 2004-217178 may be employed.

In step 555 of FIG. 5, the CPU may set a lower limit value for the second target acceleration G2. For example, in step 555, the CPU may set the lower limit value of the second target acceleration G2 to 0 m / s ² . That is, when the second target acceleration G2 becomes a negative value (acceleration for decelerating the host vehicle), the CPU sets the second target acceleration G2 set to the set target acceleration Gf to 0 m / s ^2. You may fix it. According to this configuration, the current vehicle speed can be maintained in step 565 when the target acceleration Gtgt for ACC / CC control is a positive value. As a result, the host vehicle does not accelerate despite the situation where the target acceleration Gtgt for ACC / CC control is a positive value (that is, the situation where the host vehicle may be accelerated). That is, it is possible to inform that the failure has occurred, that is, the failure state 403.

  The above normal conditions, fail conditions, recovery conditions, and standby conditions are examples, and are not limited thereto. For example, the normal condition may include a condition as to whether information has been normally acquired from various sensors.

  Each of the normal condition, the fail condition, and the recovery condition may include a confidence level condition regarding the position of the host vehicle. The degree of confidence is an index value indicating how reliable the section of the road on which the vehicle is traveling is specified. By adding the confidence level to each of the above conditions, it is possible to determine whether the acquired road information is highly reliable. The navigation ECU 20 can calculate an estimation error of the position of the host vehicle using a known method such as a Kalman filter based on the GPS signal, map information, and the like, and can calculate the confidence level according to the estimation error. . The navigation ECU 20 outputs the confidence level to the driving support ECU 10. For example, the normal condition may include a condition as to whether the degree of confidence is a predetermined value or more. The fail condition may include a condition as to whether or not the confidence level has become smaller than a predetermined value. The recovery condition may include a condition as to whether the confidence level has recovered to a predetermined value or more.

  The vehicle travel control device according to the present embodiment is applied to a vehicle capable of executing constant speed control and follow-up inter-vehicle distance control, or a vehicle configured to be capable of executing only constant speed control, or follow-up. You may apply to the vehicle comprised so that execution of only inter-vehicle distance control was possible. When the vehicle travel control device according to the present embodiment is applied to a vehicle configured to be able to execute only constant speed control, the target acceleration calculation unit 206a calculates a target acceleration Gtgt for constant speed control. The vehicle control unit 206 selects and executes either one of constant speed control (CC) and speed adjustment support control. When the set target acceleration Gf is smaller than the target acceleration Gtgt calculated by the constant speed control, the vehicle control unit 206 performs deceleration control using the set target acceleration Gf. On the other hand, when the set target acceleration Gf is equal to or greater than the target acceleration Gtgt calculated by constant speed control, the vehicle control unit 206 performs deceleration control using the target acceleration Gtgt.

DESCRIPTION OF SYMBOLS 10 ... Driving assistance ECU, 20 ... Navigation ECU, 30 ... Engine ECU, 40 ... Brake ECU, 201 ... Road information acquisition part, 202 ... 1st target acceleration calculation part, 203 ... Curvature radius estimation part, 204 ... 2nd target acceleration Calculation unit, 205 ... target acceleration selection unit, 206 ... vehicle control unit, 207 ... system state determination unit.

Claims (1)

Constant speed control that causes the host vehicle to travel at a constant speed according to a target speed, and the following inter-vehicle distance that causes the host vehicle to follow the preceding vehicle while maintaining a predetermined distance between the host vehicle and the preceding vehicle. Vehicle control means for executing at least one of the control,
Information acquisition means for receiving road information regarding the position of the host vehicle and a road ahead of the host vehicle from a navigation device mounted on the host vehicle;
Detecting means for detecting traveling state information representing the current traveling state of the host vehicle;
When the host vehicle reaches the predetermined section so that the lateral acceleration of the host vehicle is not more than a predetermined allowable lateral acceleration when the host vehicle travels on a predetermined section of the road ahead of the host vehicle. First target acceleration calculating means for calculating a first target acceleration, which is a target value of acceleration for decelerating the vehicle, based on the road information and the running state information;
A radius-of-curvature estimating means for estimating a radius of curvature of a road on which the host vehicle is currently traveling based on the traveling state information;
The second target acceleration, which is a target value of acceleration for decelerating the host vehicle so that the lateral acceleration of the host vehicle becomes equal to or less than the allowable lateral acceleration after a predetermined time, is set to the estimated radius of curvature and the running state. Second target acceleration calculating means for calculating based on the information;
When the information acquisition unit can normally acquire the road information from the navigation device, it is determined that the current device state is a normal state, and the information acquisition unit normally acquires the road information from the navigation device. State determination means for determining that the current device state is a fail state when not completed;
Target acceleration selection means for determining a set target acceleration according to the current device state determined by the state determination means;
With
The vehicle control means includes
When executing the constant speed control, a constant speed control acceleration, which is a target value of acceleration for accelerating or decelerating the host vehicle so that the speed of the host vehicle matches the target speed, is set as a third target acceleration. Decide
When executing the following inter-vehicle distance control, the following inter-vehicle distance is a target value of acceleration for accelerating or decelerating the own vehicle so that the inter-vehicle distance between the own vehicle and the preceding vehicle is maintained at the predetermined distance. A distance control acceleration is determined as the third target acceleration;
The target acceleration selecting means is
When the current device state is the normal state, the smaller one of the first target acceleration and the second target acceleration is determined as the set target acceleration,
When the current device state is the fail state, the second target acceleration is determined as the set target acceleration;
The vehicle control means includes
When the set target acceleration is smaller than the third target acceleration, the speed of the host vehicle is controlled by controlling the acceleration of the host vehicle so that the actual acceleration of the host vehicle matches the set target acceleration. ,
When the third target acceleration is less than or equal to the set target acceleration, the speed of the host vehicle is controlled by controlling the acceleration of the host vehicle so that the actual acceleration of the host vehicle matches the third target acceleration. ,
Vehicle travel control device.

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