JP2007176265A - Travelling control device of vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a travelling control device of a vehicle capable of certainly performing changing of a travelling route to avoid collision against an obstacle, etc. while reducing the possibility of making an occupant feel odd due to an improper change of the travelling route. <P>SOLUTION: Necessity Da of the travelling route change to avoid the collision against the obstruction is computed (S120) when the obstruction exists in front of the travelling route of the self vehicle and it is necessary to carry out changing control of the travelling route by controlling a steering angle of a rear wheel (S70, 80), reliability Db of information provided by a radar sensor 54 and a CCD camera 56 concerning a vehicle circumference is computed (S130), the bigger a size of a controlled variable of a steering angle of the front and rear wheels becomes in the same phase direction as the front wheel the higher the reliability Db of the provided information is, and a ratio of moving quantity in the lateral direction of the vehicle against variation of a yaw rate of the vehicle is controlled to be larger (S140 to 170). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a vehicle travel control device, and more particularly, to a vehicle travel control device that changes a travel route of a vehicle by moving the vehicle laterally while traveling based on travel environment information around the vehicle. Related.

In vehicles such as automobiles, it has been determined whether or not there are obstacles ahead of the vehicle, and when there are obstacles in front of the vehicle, there are various types of traveling control devices that control the traveling of the vehicle so that the vehicle does not collide with the obstacles. The thing of the structure of is known. For example, in Patent Document 1 below, an obstacle is detected by detecting a relative distance and a relative speed with an obstacle in front of the vehicle and controlling at least one of a braking force and a steering angle of a front wheel based on the relative distance and the relative speed. A traveling control device for avoiding a collision with the vehicle is described.
JP-A-2005-132172

  Generally, when the rudder angle of the front wheels is controlled so that the vehicle does not collide with an obstacle, the vehicle is moved laterally by changing the direction of the vehicle with respect to the road, and then the direction of the vehicle is changed along the road. Since the travel route of the vehicle is changed by returning to the direction, the obstacle in front of the vehicle and the situation around the vehicle must be accurately detected and determined. In particular, when the detection and judgment of obstacles and surrounding conditions of the vehicle are inaccurate, the occupant of the vehicle is caused by an improper change in the travel route accompanied by an unnatural change in the direction of the vehicle. May not only feel uncomfortable, but also may not be able to reliably avoid a collision with an obstacle.

  The present invention has been made in view of the above-described problems in the conventional travel control device that changes the travel route so that the vehicle does not collide with an obstacle. The main problem of the present invention is the vehicle to be acquired. By controlling the change of the driving route in consideration of the reliability of the driving environment information around the vehicle, it is possible to reduce the possibility that the occupant of the vehicle will feel uncomfortable due to the inappropriate change of the driving route, To reliably change the travel route for avoiding a collision.

  According to the present invention, the main problem described above is the configuration of claim 1, that is, the information acquisition means for acquiring the travel environment information around the vehicle, and the lateral direction while traveling the vehicle based on the travel environment information. Means for determining the necessity of changing the travel route of the vehicle by moving, and when there is a need to change the travel route, the vehicle is moved laterally while the vehicle is traveling by turning at least the steered wheels. In the vehicle travel control device having the travel route changing means for changing the travel environment information, the means for determining the reliability of the travel environment information, and when the reliability of the travel environment information is high or the necessity is high, Control that increases the ratio of the amount of lateral movement of the vehicle to the amount of change in the yaw rate of the vehicle when the travel route is changed compared to when the reliability of the travel environment information is low or when the necessity is low Is achieved by the running controller for the vehicle, characterized in that it comprises a stage.

  Further, according to the present invention, in order to effectively achieve the above-described main problems, in the configuration of claim 1, the control means is more suitable when the necessity is high than when the necessity is low. The ratio of the amount of lateral movement of the vehicle to the amount of change in the yaw rate of the vehicle when the travel route is changed is configured to increase (configuration of claim 2).

  According to the present invention, in order to effectively achieve the main problems described above, in the configuration according to claim 1 or 2, the travel route changing means includes front wheel steering angle varying means and rear wheel steering angle varying means. The control means is configured to increase the ratio by controlling the rudder angle of the rear wheels to the same phase as the rudder angle of the front wheels (configuration of claim 3).

  According to the present invention, in order to effectively achieve the main problems described above, in the configuration of claim 3, the control means can change the front wheel steering angle varying means and the rear wheels according to the necessity. The amount of lateral movement of the vehicle is controlled by controlling the rudder angle varying means, and the ratio of the amount of control of the rudder angle of the rear wheel with respect to the necessity is gradually reduced after the lateral movement of the vehicle is started. (Configuration of claim 4).

  According to the present invention, in order to effectively achieve the main problems described above, in the configuration of claim 3, the control means can change the front wheel steering angle varying means and the rear wheels according to the necessity. The amount of lateral movement of the vehicle is controlled by controlling the steering angle varying means, and the control means includes means for determining the traveling direction of the vehicle desired by the vehicle occupant, and the vehicle travel desired by the vehicle occupant When the direction and the actual traveling direction of the vehicle are different, the control amount of the steering angle of the rear wheel is reduced (configuration of claim 5).

  According to the present invention, in order to effectively achieve the main problems described above, the means for determining the necessity of changing the travel route in the configuration of claims 1 to 5 includes the travel environment information. And determining whether or not there is an obstacle ahead of the traveling route of the vehicle, and determining that it is necessary to change the traveling route when it is determined that there is an obstacle. 6 configuration).

  According to the present invention, in order to effectively achieve the main problems described above, in the configuration of claims 1 to 6, the travel control device includes a plurality of information acquisition means, and the travel environment information The means for determining the reliability of the driving environment information is configured to determine that the reliability of the driving environment information is higher as the mutual matching degree of the driving environment information acquired by the plurality of information acquisition means is higher. ).

  According to the present invention, in order to effectively achieve the above-mentioned main problems, in the configuration of the above-described claims 1 to 7, the means for determining the necessity is another travel path by a driver's driving operation. Means for determining the possibility of a change of course, and is configured to determine that the necessity is higher as the possibility of the change of course is lower.

  According to the present invention, in order to effectively achieve the above-mentioned main problems, in the configuration of the above-described claims 1 to 8, the control means changes the course to another traveling path by the driving operation of the driver. And a means for determining the possibility that the route is changed. When the possibility of the route change is high, the change of the travel route by the travel route change means is stopped (configuration of claim 9).

  In general, when changing the travel route of a vehicle by moving the vehicle laterally by traveling control of the vehicle, the greater the ratio of the lateral movement amount of the vehicle to the change amount of the yaw rate of the vehicle, the greater the travel route. Since the change in the direction of the vehicle with respect to the vehicle becomes smaller, it is possible to reduce the possibility that the vehicle occupant feels uncomfortable due to an unnatural change in the yaw rate of the vehicle. Further, the larger the ratio of the lateral movement amount of the vehicle to the change amount of the yaw rate of the vehicle, the smaller the amount of steering wheel turning and turning back and the smaller the amount of yaw movement of the vehicle and its change. Accordingly, the vehicle can be efficiently moved in the lateral direction, and the burden on the tires necessary for yawing the vehicle can be reduced.

  However, the larger the ratio of the lateral movement of the vehicle to the amount of change in the yaw rate of the vehicle, the smaller the change in the direction of the vehicle with respect to the travel path. Therefore, if the driver is about to change course to a branch road, etc. It is difficult to change the direction of the vehicle in the direction of a branch road or the like, and the deviation between the traveling direction of the vehicle and the traveling direction intended by the driver tends to increase.

  According to the configuration of claim 1, the reliability of the travel environment information is determined, and when the reliability of the travel environment information is high, the yaw rate of the vehicle when the travel route is changed compared to when the reliability of the travel environment information is low Since the ratio of the amount of lateral movement of the vehicle to the amount of change in the vehicle is increased, when the reliability of the driving environment information is high, the vehicle occupant may feel uncomfortable due to an unnatural change in the yaw rate of the vehicle The vehicle can be efficiently moved in the lateral direction while reducing the tire load, and when the reliability of the driving environment information is low, the vehicle traveling direction and the traveling direction intended by the driver It is possible to prevent an increase in the deviation.

  Further, according to the configuration of the second aspect, when the necessity of changing the travel route of the vehicle is high, the lateral direction of the vehicle with respect to the amount of change in the yaw rate of the vehicle when the travel route is changed is compared to when the necessity is low. Since the ratio of travel is increased, when there is a high need to change the travel route of the vehicle, the tire burden is reduced by reducing the possibility that the vehicle occupant will feel uncomfortable due to unnatural changes in the yaw rate of the vehicle. It is possible to efficiently move the vehicle in the lateral direction while reducing the amount of vehicle travel, and when the necessity is low, it is possible to prevent the deviation between the traveling direction of the vehicle and the traveling direction intended by the driver from becoming large. be able to.

  According to the configuration of the third aspect, the ratio of the lateral movement amount of the vehicle to the change amount of the yaw rate of the vehicle is increased by controlling the steering angle of the rear wheel in the same phase as the steering angle of the front wheel. The amount of change in the yaw rate of the vehicle can be reliably reduced and the amount of lateral movement of the vehicle can be increased.

  According to the fourth aspect of the present invention, the lateral movement amount of the vehicle is controlled by controlling the front wheel rudder angle varying means and the rear wheel rudder angle varying means according to the necessity of changing the travel route of the vehicle. Since the ratio of the control amount of the steering angle of the rear wheels to the necessity after the vehicle starts moving in the lateral direction is gradually reduced, the vehicle can be effectively moved in the lateral direction at the beginning of the control, As the control progresses, the ratio of the control amount of the steering angle of the rear wheel to the necessity is reduced, thereby reliably reducing the possibility that the deviation between the traveling direction of the vehicle and the traveling direction intended by the driver will increase. Can do.

  According to the configuration of claim 5, the lateral movement amount of the vehicle is controlled by controlling the front wheel rudder angle varying means and the rear wheel rudder angle varying means according to the necessity of changing the travel route of the vehicle. When the traveling direction of the vehicle desired by the vehicle occupant is determined and the traveling direction of the vehicle desired by the vehicle occupant differs from the actual traveling direction of the vehicle, the amount of control of the steering angle of the rear wheel is reduced. Therefore, it is possible to reliably prevent the deviation between the traveling direction of the vehicle and the traveling direction intended by the driver.

  According to the configuration of the sixth aspect, it is determined whether there is an obstacle ahead of the traveling route of the own vehicle based on the traveling environment information, and the traveling route is changed when it is determined that there is an obstacle. Therefore, if there is an obstacle in front of the vehicle, the traveling route can be changed to reliably prevent the collision with the obstacle.

  Further, according to the configuration of the seventh aspect, since the reliability of the traveling environment information is determined to be higher as the mutual degree of matching of the traveling environment information acquired by the plurality of information acquisition means is higher, the reliability of the traveling environment information is increased. The degree can be reliably determined.

  Further, according to the configuration of the eighth aspect, the possibility that the driver changes the course to the branch road is determined, and the lower the possibility that the driver changes the course to the other road due to the driving operation, the more the vehicle travels. Since it is determined that the need to change the route is high, the lateral direction of the vehicle with respect to the amount of change in the yaw rate of the vehicle when the route is changed as the possibility of changing the route to another route by the driver's driving operation is lower The ratio of the amount of movement of the vehicle can be increased, and the vehicle can be effectively moved in the lateral direction.

  According to the ninth aspect of the present invention, the change of the travel route by the travel route changing means is stopped when there is a high possibility that the route is changed to another travel route by the driving operation of the driver. When a route is to be changed to another travel route by an operation, the change of the travel route by the travel route changing means can be canceled so that the desire is satisfied.

[Preferred embodiment of problem solving means]
According to one preferred aspect of the present invention, in the configuration of the above first to ninth aspects, the information acquisition means acquires at least information on the condition of the road and the presence / absence of obstacles as driving environment information around the vehicle. (Preferred embodiment 1).

  According to another preferred aspect of the present invention, in the configuration of the above-mentioned claims 1 to 9 or the preferred aspect 1, the means for determining the necessity of changing the travel route of the vehicle changes the travel route of the vehicle. The higher the degree of necessity or the higher the possibility that the travel route of the vehicle can be changed, the higher the necessity of changing the travel route of the vehicle is determined (preferred aspect 2).

  According to another preferred aspect of the present invention, in the configuration of the above-mentioned claims 1 to 9 or the preferred aspect 1 or 2, the travel route changing means is at least a steering wheel when it is necessary to change the travel route. The vehicle is moved in the lateral direction by turning the vehicle and decelerating the vehicle to change the travel route (preferred aspect 3).

  According to another preferred embodiment of the present invention, in the configuration of the above-mentioned claims 4 to 9 or the preferred embodiments 1 to 3, the control means is operated with the passage of time after the start of movement of the vehicle in the lateral direction. The ratio of the control amount of the steering angle of the rear wheel to the necessity is gradually decreased by gradually decreasing the magnitude of the control amount of the wheel steering angle (preferred aspect 4).

  According to another preferred embodiment of the present invention, in the configuration of the above-described claims 5 to 9 or the preferred embodiments 1 to 4, the control means controls the vehicle traveling direction desired by the vehicle occupant and the actual vehicle state. It is configured to reduce the amount of control of the steering angle of the rear wheels when a situation different from the traveling direction has passed for a reference time or longer (Preferable aspect 5).

  According to another preferred aspect of the present invention, in the configuration of the above claims 6 to 9 or the preferred aspects 1 to 5, the means for determining the necessity of changing the travel route is that the vehicle is an obstacle. The higher the possibility of collision, the higher the necessity of changing the travel route is determined (preferred aspect 6).

  According to another preferred aspect of the present invention, in the configuration of the preferred aspect 6 described above, the means for determining the necessity includes the size of the obstacle, the position of the obstacle, and the relative distance of the own vehicle with respect to the obstacle. And based on relative speed, it is comprised so that the possibility that the own vehicle may collide with an obstacle is determined (preferred aspect 7).

  According to another preferred aspect of the present invention, in the configuration of any one of claims 7 to 9 or preferred aspects 1 to 7, at least a plurality of information acquisition means includes means for wirelessly acquiring travel environment information. And a means for acquiring travel environment information by imaging (preferred aspect 8).

  According to another preferred aspect of the present invention, in the configuration of the above-mentioned claims 7 to 9 or the preferred aspects 1 to 8, the means for determining the reliability of the travel environment information is acquired by a plurality of information acquisition means. It is configured to determine that the reliability of the traveling environment information is higher as the degree of mutual matching of the information regarding at least the traveling route is higher (preferred aspect 9).

  According to another preferred aspect of the present invention, in the configuration of the above-mentioned claims 7 to 9 or the preferred aspects 1 to 9, the means for determining the reliability of the travel environment information is acquired by a plurality of information acquisition means. It is configured to determine that the reliability of the traveling environment information is higher as the mutual matching degree of the information regarding the presence / absence, size, and position of the obstacle is higher (preferred aspect 10).

  According to another preferred aspect of the present invention, in the configuration of the above-mentioned claim 8 or 9 or the preferred aspects 1 to 10, the possibility of changing the course to another traveling path by the driving operation of the driver is provided. The means for determining is configured to determine the possibility of a course change based on at least the presence or absence of another traveling path (preferred aspect 11).

  According to another preferable aspect of the present invention, in the configuration of the above-mentioned claim 8 or 9 or the preferable aspects 1 to 11, the possibility of changing the course to another traveling path by the driving operation of the driver is provided. The means for determining is configured to determine the possibility of a course change based on at least the degree of difference between the vehicle traveling direction desired by the vehicle occupant and the actual traveling direction of the vehicle and the duration of the situation (preferred embodiment). 12).

  According to another preferred aspect of the present invention, in the configuration of the above-mentioned claim 9 or the preferred aspects 1 to 12, the control means changes the travel route when stopping the travel route change by the travel route changing means. It is comprised so that the magnitude | size of the control amount of a means may be decreased gradually (preferable aspect 13).

  According to another preferred embodiment of the present invention, in the configuration of the above-mentioned claims 1 to 9 or the preferred embodiments 1 to 13, the control means needs to change the travel route but cannot change the travel route. It is configured to decelerate the vehicle when possible (preferred aspect 14).

  The present invention will now be described in detail with reference to the accompanying drawings.

  FIG. 1 is a schematic diagram showing a vehicle travel control apparatus according to a first embodiment of the present invention applied to a vehicle equipped with a turning angle varying device for automatically turning left and right front wheels and a rear wheel steering device for steering rear wheels. It is a block diagram.

  In FIG. 1, 10FL and 10FR respectively indicate left and right front wheels which are steering wheels of the vehicle 12, and 10RL and 10RR respectively indicate left and right rear wheels. The left and right front wheels 10FL and 10FR, which are steering wheels, are rotated via a rack bar 18 and tie rods 20L and 20R by a rack-and-pinion type power steering device 16 driven in response to an operation of the steering wheel 14 by a driver. Steered.

  The steering wheel 14 is drivingly connected to the pinion shaft 30 of the power steering device 16 through an upper steering shaft 22, a turning angle varying device 24, a lower steering shaft 26, and a universal joint 28. In the illustrated embodiment 1, the turning angle varying device 24 is connected to the lower end of the upper steering shaft 22 on the housing 24A side, and connected to the upper end of the lower steering shaft 26 on the rotor 24B side. An electric motor 32 for driving auxiliary steering is included.

  Thus, the turning angle varying device 24 rotates the lower steering shaft 26 relative to the upper steering shaft 22, thereby automatically turning the left and right front wheels 10FL and 10FR relative to the steering wheel 14. It functions as a rudder device and is controlled by the steering control unit of the electronic control unit 34.

  The steering angle varying device 24 is also configured to function as a steering gear ratio varying device that changes the steering angle ratio of the left and right front wheels 10FL and 10FR as steering wheels with respect to the rotation angle of the steering wheel 14, that is, the steering gear ratio. May be.

  On the other hand, the left and right rear wheels 10RL and 10RR are routed via tie rods 40L and 40R by a hydraulic or electric power steering device 38 of the rear wheel steering device 36 independently of the steering of the left and right front wheels 10FL and 10FR by the driver. The rear wheel steering device 36 is controlled by the rear wheel steering unit of the electronic control device 34.

  The power steering device 16 may be either a hydraulic power steering device or an electric power steering device. Steering generated by the auxiliary wheel driving of the front wheels by the turning angle varying device 24 and transmitted to the steering wheel 14. A rack coaxial having, for example, an electric motor and a conversion mechanism such as a ball screw type that converts the rotational torque of the electric motor into a force in the reciprocating direction of the rack bar 18 so as to generate an auxiliary steering torque that reduces fluctuations in the reaction torque. The electric power steering device of the type is preferable.

  The braking force of each wheel is controlled by controlling the pressure Pi (i = fl, fr, rl, rr) in the wheel cylinders 46FL, 46FR, 46RL, 46RR, that is, the braking pressure, by the hydraulic circuit 44 of the braking device 42. It has become so. Although not shown in FIG. 1, the hydraulic circuit 44 includes an oil reservoir, an oil pump, various valve devices, and the like, and the braking pressure of each wheel cylinder is normally driven according to the depression operation of the brake pedal 48A by the driver. It is controlled by the master cylinder 48, and is individually controlled by the braking force control unit of the electronic control unit 34 as will be described in detail later if necessary.

  In the illustrated embodiment 1, the upper steering shaft 22 is provided with a steering angle sensor 50 that detects the rotation angle of the upper steering shaft as a steering angle θ, and the turning angle variable device 24 includes a housing 24A. And a rotation angle sensor 52 for detecting a relative rotation angle of the rotor 24B as a relative rotation angle θre of the lower steering shaft 26 with respect to the upper steering shaft 22, and outputs of these sensors are supplied to the electronic control unit 34. .

  The electronic control unit 34 also includes information on the situation around the vehicle detected by the radar sensor 54, particularly a signal indicating the presence or absence of a front obstacle, a relative distance Lre to the front obstacle, and a relative speed Vre to the front obstacle, a CCD camera. 56, a signal indicating image information in front of the vehicle, a signal indicating road information from the navigation device 58 and information on the position of the own vehicle, a signal indicating the vehicle speed V detected by the vehicle speed sensor 60, and an operation of the selection switch 62. A signal indicating the control mode (driving support mode or non-driving support mode) set by the control signal, a signal indicating the master cylinder pressure Pm detected by the pressure sensor 64, and the braking pressure Pi of each wheel detected by the pressure sensors 66FL to 66RR. Is input. Thus, in the illustrated embodiment, the traveling environment information around the vehicle is acquired by the radar sensor 54, the CCD camera 56, and the navigation device 58.

  Although not shown in detail in FIG. 1, the electronic control unit 34 includes a steering control unit that controls the steering angle varying device 24, a rear wheel steering control unit that controls the rear wheel steering device 36, and each wheel. A braking force control unit for controlling the braking force of the vehicle and a traveling control unit for controlling the traveling state of the vehicle. Each control unit has a CPU, a ROM, a RAM, and an input / output port device, which are bidirectional. May include microcomputers connected to each other by a common bus. Further, the steering angle sensor 50 and the rotation angle sensor 52 detect the steering angle θ and the relative rotation angle θre, respectively, with the case where the vehicle is steered or turned in the left turn direction as positive.

  As will be described later, when the control mode is set to the driving support mode by the operation of the selection switch 60, the electronic control unit 34 travels around the vehicle detected by the radar sensor 54, the CCD camera 56, and the navigation device 58. The road condition is determined based on the information, and it is determined whether there is an obstacle ahead of the traveling route of the host vehicle.

  When the electronic control unit 34 determines that there is an obstacle ahead of the traveling route of the vehicle, the electronic control unit 34 determines whether or not the traveling route needs to be changed to avoid a collision with the obstacle, It is determined whether or not the route can be changed. When it is determined that the travel route needs to be changed and the travel route can be changed, the possible change direction of the travel route (left side with respect to the current travel lane) And the right side), the reliability Da of the traveling environment information around the vehicle detected by the radar sensor 54, the CCD camera 56, and the navigation device 58 and the necessary degree Db of the traveling route change are calculated.

  Further, the electronic control unit 34 sets the target front wheel correction turning angle Δδtf and the target rear wheel steering angle δtr for changing the traveling route of the vehicle based on the reliability degree Da of the traveling environment information and the necessity degree Db of traveling route change. The turning angle varying device 24 is controlled based on the target front wheel corrected turning angle Δδtf so that the corrected turning angles of the left and right front wheels 10FL and 10FR become the target front wheel corrected turning angle Δδtf, and the left and right rear wheels 10RL and The rear wheel steering device 36 is controlled so that the steering angle of 10RR becomes the target rear wheel steering angle δtr.

  In this case, the target front wheel corrected turning angle Δδtf is calculated so as to increase as the reliability Da of the driving environment information and the necessity Db of changing the driving route increase, and the target rear wheel steering angle δtr is calculated as the reliability of the driving environment information. The higher the Da is, the larger the left and right front wheels 10FL and 10FR are in phase with the corrected turning direction.

  In addition, when the electronic control unit 34 determines that the travel route needs to be changed to avoid a collision with an obstacle, there is another vehicle in the change destination travel lane or the change destination travel. When it is determined that the travel route cannot be changed as in the case where there is no lane, the turning angle variable device 24 and the rear wheel steering device 36 are controlled during normal travel, and collision with an obstacle is avoided. The braking force of each wheel is controlled by calculating the target deceleration Gxbt of the vehicle necessary for this and controlling the braking device 42 so that the deceleration of the vehicle becomes the target deceleration Gxbt.

  In addition, the electronic control unit 34 controls the turning angle variable device 24 and the rear wheel steering device 36 during normal driving even when the control mode is set to the non-driving support mode. The control at the time of normal travel of the turning angle varying device 24 is control of the steering gear ratio that increases the steering gear ratio as the vehicle speed V increases, and the control at the time of normal travel of the rear wheel steering device 36 is performed in a low vehicle speed range. In this case, the rear wheel may be steered in the opposite phase with respect to the front wheel, and the rear wheel may be steered in the same phase with respect to the front wheel in the high vehicle speed range. It is not a summary and may be performed in any manner known in the art.

  Next, a vehicle travel control routine achieved by the electronic control unit 34 in the first embodiment will be described with reference to the flowchart shown in FIG. The control according to the flowchart shown in FIG. 2 is started by closing an ignition switch not shown in the figure, and is repeatedly executed at predetermined time intervals. At the start of control, the flag Fc is initialized to 0 prior to step 10.

  First, in step 10, a signal indicating the steering angle θ is read, and in step 20, it is determined whether or not the control mode is set to the driving support mode by operating the selection switch 60. When a negative determination is made, the process proceeds to step 90, and when an affirmative determination is made, the process proceeds to step 30.

  In step 30, it is determined whether or not the flag Fc is 1, that is, whether or not traveling control by controlling the steering angle of the front and rear wheels has already been started, and when a negative determination is made. Proceed to step 70, and if an affirmative determination is made, proceed to step 40.

  In step 40, it is determined whether or not a condition for ending the running control by controlling the steering angle of the front and rear wheels is satisfied. If an affirmative determination is made, the process proceeds to step 60, and a negative determination is made. Sometimes go to step 50.

In this case, the running control end condition by controlling the front and rear wheel steering angles is
(1) The change of the travel route has been completed (2) There are no obstacles (3) The vehicle has stopped (4) Any of the events that occurred in the radar sensor 54 etc. It may be.

  In step 50, is the driver willing to change the course to another road, such as a branch road, an interchange exit on a highway, an access path to a service area or a parking area, a retreat area, etc. If a negative determination is made, the process proceeds to step 100. If an affirmative determination is made, the flag Fc is reset to 0 in step 60, and the steering angles of the front and rear wheels are set. The control amount is gradually reduced to the control amount at the time of normal traveling, which is calculated in the same manner as in step 90 described later, and then proceeds to step 90.

In this case, the determination as to whether or not the driver intends to change the course to another route is as follows:
(1) It is determined from the information from the CCD camera 56 or the navigation device 58 that there is another travel path. (2) The driver is steering in the direction toward the other travel path. (3) The driver is heading. It may be performed by determining whether or not two conditions are satisfied that the situation where the magnitude of the difference between the current direction and the actual direction of the vehicle is abnormal in the reference value continues for the reference time or more.

  In step 70, the vehicle travels in a manner known in the art based on the situation information of the surroundings of the vehicle detected by the radar sensor 54 and the image information of the front of the vehicle detected by the CCD camera 56. It is determined whether there is an obstacle such as a stopped vehicle in front of the route. If a negative determination is made, the process proceeds to step 90. If an affirmative determination is made, the process proceeds to step 80.

  In step 80, the steering angle of the front and rear wheels is controlled based on the size (especially width) of the obstacle detected by the radar sensor 54, the position of the obstacle, the relative distance Lre of the host vehicle to the obstacle, and the relative speed Vre. It is determined whether or not the travel route change control is necessary. When an affirmative determination is made, the process proceeds to step 100. When a negative determination is made, at step 90, the front and rear wheels during normal driving are determined. After the control of the steering angle is executed, the process returns to step 10.

  In step 100, it is determined whether or not the travel route can be changed so that the travel lane becomes an adjacent travel lane in order to avoid a collision with an obstacle, and a negative determination is performed. When the determination is affirmative, the routine proceeds to step 180. When the determination is affirmative, the flag Fc is reset to 1 at step 110 and then the process proceeds to step 120.

In this case, it is determined whether or not the travel route can be changed.
(1) There is an adjacent lane where the travel route can be changed. (2) A determination is made as to whether or not two conditions exist such that there is no other vehicle or the like obstructing the lane change of the own vehicle. May be performed.

  In step 120, the travel route change degree in order to avoid a collision with an obstacle is calculated by changing the travel route in the change direction determined to be possible in step 100. In this case, the necessary degree Da of the travel route change is higher as the relative distance Lre to the obstacle is shorter, higher as the relative speed Vre with respect to the front obstacle is larger, and higher as the size (especially width) of the obstacle is larger. On the contrary, the larger the amount of deceleration operation or avoidance steering operation by the driver, the lower the calculation.

  In step 130, the degree of reliability Db of the acquired information related to the situation around the vehicle detected by the radar sensor 54 and the acquired information related to the front of the vehicle detected by the CCD camera 56 is calculated. In this case, the reliability Db of the acquired information is calculated so as to increase as the degree of coincidence between the road condition detected by the CCD camera 56 and the road information obtained from the navigation device 58 increases, and by the radar sensor 54. Calculation is performed such that the higher the degree of matching of the detected obstacle and the obstacle detected by the CCD camera 56, the higher the degree of coincidence.

  In step 140, the travel route of the host vehicle is changed from the map corresponding to the graph shown in FIG. 3 based on the direction to change the travel route, the necessary degree Da of the travel route change, and the reliability Db of the acquired information. The target front wheel corrected turning angle Δδtf of the left and right front wheels 10FL and 10FR for the purpose is calculated, and in step 150, the graph shown in FIG. 4 is obtained based on the required degree Da of the travel route change and the reliability degree Db of the acquired information. The target rear wheel steering angle δtr of the left and right rear wheels 10RL and 10RR for changing the traveling route of the host vehicle is calculated from the corresponding map.

  In step 160, the turning angle varying device 24 is controlled based on the target front wheel corrected turning angle Δδtf so that the corrected turning angles of the left and right front wheels 10FL and 10FR become the target front wheel corrected turning angle Δδtf. In this case, the rear wheel steering device 36 is controlled so that the steering angles of the left and right rear wheels 10RL and 10RR become the target rear wheel steering angle δtr, and then the process returns to step 10.

In step 180, control of the steering angle of the front and rear wheels during normal driving is executed in the same manner as in step 90 described above, and in step 190, it is necessary to avoid collision with an obstacle. The target deceleration Gxbt of the vehicle is calculated according to, for example, the following equation 1, and in step 200, the braking force of each wheel is controlled by controlling the braking device 42 so that the vehicle deceleration becomes the target deceleration Gxbt. Is done. In the following formula 1, α is a positive constant coefficient.
Gxbt = α (Lre / Vre) (1)

  Thus, according to the illustrated embodiment, when the control mode is set to the driving support mode, an affirmative determination is made in step 20, whereby the travel control after step 30 is executed, and the control mode is set to the non-driving support. When the mode is set, a negative determination is made in step 20, and even if the control mode is set to the driving support mode, there is an obstacle such as a stopped vehicle in front of the traveling route of the own vehicle. If there is no obstacle in the traveling route ahead of the vehicle, but it is not necessary to change the traveling route by controlling the steering angle of the front and rear wheels, a negative determination is made in steps 70 and 80, respectively. Thus, in step 90, control of the steering angle of the front and rear wheels during normal traveling is executed.

  On the other hand, when there is an obstacle on the traveling route ahead of the vehicle and it is necessary to change the traveling route by controlling the steering angle of the front and rear wheels, an affirmative determination is made in steps 70 and 80, respectively. In step 100, it is determined whether or not the travel route can be changed so that the travel lane becomes an adjacent travel lane in order to avoid a collision with an obstacle.

(Case 1) When the travel route can be changed and the possibility of changing to another travel route is low. In this case 1, as shown in FIG. 7, for example, the vehicle 12 travels in two lanes. The vehicle travels along the travel route 106 of the lane 104 on the left side of the road 102, the obstacle 110 exists in the travel route 106 ahead of the host vehicle, and there are no other vehicles on the right lane 108, so There are no roads.

  In this case, a negative determination is made in step 50 and an affirmative determination is made in step 100, and the left and right front wheels 10FL and 10FR are adjacent so that the vehicle moves to the adjacent lane in steps 120 to 170. The steering wheel of the left and right rear wheels 10RL and 10RR is controlled in phase with the front wheels. Therefore, the vehicle 12 moves to the right while traveling without a large yaw rate change, and moves to the right lane 108 from the left lane 104, thereby passing the right side of the obstacle 110.

  As shown in FIG. 8, even if a branch road 112 or the like is present in front of the side on which the vehicle 12 moves, the left and right front wheels 10FL and 10FR are in the direction along the travel road 102, and the driver If it is determined that the route is not going to be changed, the possibility of changing the route to another traveling route is low, and thus the same control as in the above case where the branch route 112 or the like does not exist is performed.

  When the lane change is completed and there is no possibility of a collision with the obstacle 110, an affirmative determination is made in step 40, and the control amount of the front wheels and the rear wheels is gradually reduced, so that the vehicle 12 moves. Travel along the following lane 108.

(Case 2) When the travel route can be changed and there is a high possibility of changing the route to another travel route In this case 2, as shown in FIG. 9, for example, the vehicle 100 travels in two lanes. The vehicle travels along the travel route 106 of the lane 104 on the left side of the road 102, the obstacle 110 exists in the travel route 106 ahead of the host vehicle, and there are no other vehicles on the right lane 108, so There is a road 112 or the like, and the driver is steered toward the branch road 112 or the like.

  As in the case of (1) above, the control of the steering angle of the front wheels and the rear wheels is started and the movement of the vehicle is started. However, the driver is willing to change the course and the course can be changed to another running path. If it is determined that the vehicle performance is high, an affirmative determination is made in step 50, and the control amount of the front wheels and the rear wheels is gradually decreased, so that the vehicle 12 gradually changes yaw in a direction toward the branch road 112 and the like. Thus, the driver's intention to drive is gradually reflected greatly, and finally the vehicle 12 is driven so as to enter the branch path 112 or the like based on the driver's intention to drive.

(Case 3) When it is not possible to change the travel route In this case 3, as shown in FIG. 10, for example, the vehicle 12 travels along the travel route 106 in the lane 104 on the left side of the two-lane travel route 102. There is an obstacle 110 in the traveling route 106 in front of the host vehicle, and therefore it is necessary to move the vehicle 12 to the right lane 108, but there are other vehicles 114 etc. in the right lane 108, This is a situation where the vehicle 12 cannot be moved to the right lane 108 or a situation where the travel route is a one-lane travel route and the travel route cannot be changed.

  In this case, a negative determination is made in step 100, and in step 180, the turning angle variable device 24 and the rear wheel steering device 36 are controlled during normal travel, and in steps 190 and 200, The vehicle is decelerated by automatic braking so as not to collide with the obstacle, and the vehicle stops before the obstacle.

  As can be understood from the above description, according to the first embodiment shown in the figure, there is an obstacle such as a stop vehicle in front of the traveling route of the own vehicle, and the traveling route change control by controlling the steering angle of the front and rear wheels is necessary. In some cases, the collision with the obstacle can be avoided by changing the traveling route as long as the traveling route can be changed so that the traveling lane becomes the adjacent traveling lane in order to avoid the collision with the obstacle. As described above, the corrected turning angles of the left and right front wheels 10FL and 10FR and the steering angles of the left and right rear wheels 10RL and 10RR are automatically controlled, so that the driving route is changed without requiring the driver to perform a collision with an obstacle. Can be avoided.

  Further, according to the first embodiment shown in the drawing, the target front wheel corrected turning angle Δδtf of the left and right front wheels 10FL and 10FR corresponds to the graph shown in FIG. 3 based on the necessity degree Da of the travel route change and the reliability degree Db of the acquired information. The target rear wheel steering angle δtr of the left and right rear wheels 10RL and 10RR is calculated from the map corresponding to the graph shown in FIG. 4 on the basis of the necessity degree Da of the travel route change and the reliability degree Db of the acquired information. The control amount of the steering angle of the front and rear wheels becomes larger as the necessity degree Da of the travel route change and the reliability degree Db of the acquisition information are higher, and the control amount of the rear wheel steering angle is larger than that of the acquisition information. Since the higher the degree of reliability Db is, the larger the direction in the same direction as the front wheels is, the higher the degree of necessity Da and the degree of reliability Db, the less likely the vehicle occupants will feel uncomfortable due to unnatural changes in the yaw rate of the vehicle. Reduce the burden of However, the lateral movement of the vehicle can be efficiently performed, and conversely, the lower the necessary degree Da and the reliability degree Db, the greater the deviation between the traveling direction of the vehicle and the traveling direction intended by the driver. The prevention effect can be increased.

  In the case of a conventional travel control device, as shown in FIG. 11, it is unavoidable that the yaw rate of the vehicle changes greatly due to the travel path change control, and therefore the burden on the tire is avoided. However, according to the illustrated embodiment, the vehicle can be moved laterally without greatly changing the yaw rate of the vehicle, so that the burden on the tire is greatly reduced as compared with the case of the conventional travel control device. be able to.

  In particular, according to the first embodiment shown in the figure, it is determined in step 50 whether or not the driver has an intention to change the course, and it is determined that the driver has an intention to change the course. In step 60, the control amount of the steering angle of the front wheels and the rear wheels is gradually reduced to the control amount during normal driving, and then the control of the steering angles of the front wheels and the rear wheels is terminated. Can drive the vehicle so that the vehicle heads for a branch road or the like according to its own intention.

  Further, according to the first embodiment shown in the figure, a radar sensor 54, a CCD camera 56, and a navigation device 58 are provided as information acquisition means, and the higher the degree of matching of the driving environment information around the vehicle detected by these, the higher the degree of reliability Db. Therefore, the reliability Db of the acquired information can be calculated more accurately than when the information acquiring means is one or two of the above means.

  Also, according to the first embodiment shown in the figure, when there is an obstacle ahead of the traveling route of the own vehicle and it is necessary to change the traveling route, but the traveling route cannot be changed, step 100 is performed. In this case, a negative determination is made and steps 180 to 200 are executed, so that it is possible to reliably prevent the control of the steering angle of the front and rear wheels from being unnecessarily continued and from being unable to travel on the traveling road due to this. In addition, the vehicle can be reliably decelerated to stop the vehicle before the obstacle, and the vehicle can be reliably prevented from colliding with the obstacle.

  FIG. 5 shows a vehicle travel control device according to a second embodiment of the present invention applied to a vehicle equipped with a turning angle varying device that automatically steers left and right front wheels and a rear wheel steering device that steers rear wheels. It is a flowchart which shows the principal part of the traveling control routine of a vehicle. In FIG. 5, the same step numbers as those shown in FIG. 2 are assigned to the same steps as those shown in FIG. The same applies to FIG. In the second embodiment, the count value N of the counter is initialized to 0 prior to step 10.

  In the second embodiment, as shown in FIG. 5, when an affirmative determination is made in step 100, the flag Fc is reset to 1 in step 110, and in step 100, The count value N of the counter indicating the number of times that the affirmative determination has been made is incremented by 1, and then the routine proceeds to step 120.

  When step 150 is completed, in step 155, the magnitude of the target rear wheel steering angle δtr for changing the traveling route of the host vehicle with δtro being a small positive constant is reduced by (N−1) δtro. As a result, the magnitude of the target rear wheel steering angle δtr is corrected gradually, and then the routine proceeds to step 160. The other steps of the second embodiment are executed in the same manner as in the first embodiment.

  Therefore, according to the second embodiment, the same effect as in the first embodiment can be obtained, and the target rear wheel steering angle δtr is gradually decreased as the control of the travel route change is continued. In the initial stage of the route change control, the driver drives the vehicle so that the direction of the vehicle is in accordance with his / her intention as the drive route change control is continued while ensuring the effect of the route change sufficiently. It is possible to gradually shift to a possible situation.

  As the travel route change control is continued, the required degree Da of the travel route change decreases and the amount of control of the steering angle of the front wheels also gradually decreases. Therefore, as the travel route change control continues, the target rear wheel Even if the steering angle δtr is gradually reduced, the yaw angle of the vehicle with respect to the travel path does not become excessive.

  FIG. 6 shows a vehicle travel control device according to a second embodiment of the present invention applied to a vehicle equipped with a turning angle varying device for automatically turning left and right front wheels and a rear wheel steering device for steering rear wheels. It is a flowchart which shows the principal part of the traveling control routine of a vehicle.

In the third embodiment, as shown in FIG. 6, when step 170 is completed, the target deceleration Gxbt of the vehicle necessary for reducing the possibility of collision with an obstacle is determined in step 172. For example, the calculation is performed according to the following equation (2). In step 174, the braking force of each wheel is controlled by controlling the braking device 42 so that the vehicle deceleration becomes the target deceleration Gxbt, and then the process returns to step 10. . In the following equation 2, β is a constant positive coefficient smaller than α in equation 1. In the third embodiment, the other steps are executed in the same manner as in the first embodiment.
Gxbt = β (Lre / Vre) (2)

  Therefore, according to the third embodiment, the same effect as in the first embodiment can be obtained, and the vehicle is decelerated even when the travel route needs to be changed and the travel route can be changed. Therefore, the travel route can be changed while decelerating the vehicle, whereby the travel route can be changed safely and reliably compared to the case of the first embodiment.

  In particular, according to the third embodiment, β in the above formula 2 is smaller than α in the formula 1, so that it is possible to change the travel route while the vehicle is traveling. Therefore, it is possible to reliably prevent the vehicle from being decelerated or being stopped unnecessarily.

  Although the present invention has been described in detail with reference to specific embodiments, the present invention is not limited to the above-described embodiments, and various other embodiments are possible within the scope of the present invention. It will be apparent to those skilled in the art.

  For example, in each of the above-described embodiments, the radar sensor 54, the CCD camera 56, and the navigation device 58 are provided as information acquisition means, but any means known in the art can be used as information acquisition means. Any one of the above three means may be omitted.

  In each of the above-described embodiments, the means for varying the steering angle of the front wheels is a turning angle varying device that changes the steering transmission ratio by rotationally driving the lower steering shaft 28B relative to the upper steering shaft 28A. 24, the means for changing the rudder angle of the front wheels may be of any configuration known in the art as long as the rudder angle of the front wheels can be changed. Is a tie rod member on the steering input means side, the steering wheel side member is a tie rod member on the steering wheel side member side, and the steering transmission ratio control means is relatively on the steering wheel side member side with respect to the tie rod member on the steering input means side. It may be configured to change the rudder angle of the front wheels by linearly displacing the tie rod member.

  Further, in each of the above-described embodiments, even when an affirmative determination is made in any of Steps 40 and 50, the process proceeds to Step 60, and the condition for terminating the traveling control by controlling the steering angle of the front and rear wheels is established. Sometimes the control amount of the steering angle of the front and rear wheels is already small, so the front and rear wheels are faster than if the driver intends to change the course to another travel path. The control amount of the steering angle may be modified so as to be reduced.

Schematic configuration diagram showing one embodiment of a vehicle travel control device according to the present invention applied to a vehicle equipped with a turning angle variable device for automatically turning left and right front wheels and a rear wheel steering device for steering rear wheels. It is. It is a flowchart which shows the traveling control routine of the vehicle in an Example. It is a graph which shows the relationship between a travel route change direction, the necessity degree Da of a travel route change, the reliability Db of acquisition information, and the target front-wheel correction turning angle (DELTA) deltatf for changing the travel route of the own vehicle. It is a graph which shows the relationship between a travel route change direction, the required degree Da of travel route change, the reliability degree Db of acquisition information, and the target rear-wheel steering angle (delta) tr for changing the travel route of the own vehicle. Vehicle travel in Embodiment 2 of the vehicle travel control device according to the present invention applied to a vehicle equipped with a turning angle varying device that automatically steers left and right front wheels and a rear wheel steering device that steers rear wheels. It is a flowchart which shows the principal part of a control routine. Vehicle travel in Embodiment 2 of the vehicle travel control device according to the present invention applied to a vehicle equipped with a turning angle varying device that automatically steers left and right front wheels and a rear wheel steering device that steers rear wheels. It is a flowchart which shows the principal part of a control routine. It is explanatory drawing which shows the action | operation of Example 1 when the change of a driving route can be performed and the possibility of the course change to another driving route is low. It is explanatory drawing which shows the action | operation of Example 1 when the change of a driving | running route can be performed and the other driving | running route exists, but the possibility of the course change to another driving | running route is low. This is a case where the travel route can be changed and there is a high possibility of changing the route to another travel route. It is explanatory drawing which shows the action | operation of Example 1 when a change of a driving | running route cannot be performed. It is explanatory drawing which shows the action | operation of the conventional travel control apparatus when the change of a travel route can be performed and the possibility of the course change to another travel route is low.

Explanation of symbols

10 FR to 10 RL Wheel 24 Steering angle variable device 34 Electronic control device 36 Rear wheel steering device 42 Braking device 48 Master cylinder 50 Steering angle sensor 52 Rotation angle sensor 54 Radar sensor 56 CCD camera 58 Navigation device 60 Vehicle speed sensor 62 Selection switch 64, 66FL to 66RR Pressure sensor

Claims (9)

  Information acquisition means for acquiring travel environment information around the vehicle, means for determining the necessity of changing the travel route of the vehicle by moving the vehicle laterally based on the travel environment information, and the travel route In a vehicle travel control device comprising travel route changing means for changing the travel route by moving the vehicle laterally by turning at least the steered wheels when the vehicle needs to be changed, Means for determining the reliability of the travel environment information; and when the reliability of the travel environment information is high, the vehicle's yaw rate changes when the travel route is changed compared to when the reliability of the travel environment information is low. A vehicle travel control device comprising: control means for increasing a ratio of lateral movement amounts.   The control means increases the ratio of the lateral movement amount of the vehicle to the amount of change in the yaw rate of the vehicle when the travel route is changed when the necessity is high, compared to when the necessity is low. Item 2. The vehicle travel control device according to Item 1.   The travel route changing means includes front wheel steering angle varying means and rear wheel steering angle varying means, and the control means increases the ratio by controlling the steering angle of the rear wheels to be in phase with the steering angle of the front wheels. The vehicle travel control device according to claim 1, wherein   The control means controls the amount of lateral movement of the vehicle by controlling the front wheel rudder angle varying means and the rear wheel rudder angle varying means according to the necessity, and after the vehicle starts moving in the lateral direction, 4. The vehicle travel control apparatus according to claim 3, wherein a ratio of a control amount of a rear wheel steering angle to a necessity is gradually reduced.   The control means controls the amount of lateral movement of the vehicle by controlling the front wheel rudder angle varying means and the rear wheel rudder angle varying means according to the necessity, and the control means is desired by a vehicle occupant. A means for determining a traveling direction of the vehicle, wherein when the traveling direction of the vehicle desired by the vehicle occupant is different from the actual traveling direction of the vehicle, the control amount of the steering angle of the rear wheel is reduced. The vehicle travel control apparatus according to claim 3.   The means for determining the necessity of changing the travel route determines whether there is an obstacle ahead of the travel route of the host vehicle based on the travel environment information, and travels when it is determined that there is an obstacle. 6. The vehicle travel control device according to claim 1, wherein it is determined that the route needs to be changed.   The travel control apparatus has a plurality of information acquisition means, and the means for determining the reliability of the travel environment information is the travel environment information as the degree of mutual matching of the travel environment information acquired by the plurality of information acquisition means increases. The vehicle travel control device according to claim 1, wherein the reliability of the vehicle is determined to be high.   The means for determining the necessity includes a means for determining a possibility of a course change to another traveling path by a driver's driving operation, and determines that the necessity is higher as the possibility of the course change is lower. The vehicle travel control apparatus according to any one of claims 1 to 7. The control means includes means for determining the possibility of a course change to another travel path by a driver's driving operation. When the possibility of the course change is high, the travel path change means changes the travel path. 9. The vehicle travel control device according to claim 1, wherein the vehicle travel control device is stopped.

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