JP5663356B2 - Integrated control device for vehicle - Google Patents

Description

  The present invention integrates a vehicle equipped with a collision prevention control device that detects a front obstacle and prevents a collision with the obstacle by braking, and a front and rear driving force distribution control device that controls a fastening torque between front and rear shafts. The present invention relates to a control device.

  2. Description of the Related Art In recent years, various vehicle behavior control devices that control vehicle behavior have been mounted on vehicles. Furthermore, recently, a collision prevention control device that detects a front obstacle and prevents a collision between the obstacle and the host vehicle has begun to be put into practical use. Such a collision prevention control device, each vehicle behavior control device, Various cooperative controls have been considered. For example, in Japanese Patent Laid-Open No. 2000-302057 (hereinafter referred to as Patent Document 1), when it is determined that the host vehicle cannot avoid an obstacle only by a braking operation, the front / rear driving force distribution control device according to the steering operation and the vehicle behavior, The left and right driving force distribution control device, the rear wheel steering control device, and the side slip prevention control device are shifted to the avoidance travel mode, and the necessary control is performed to improve the turning ability of the vehicle according to the change of the steering operation and the vehicle behavior. A vehicle motion control device that cancels the avoidance travel mode when it is executed by each vehicle behavior control device and detects the end of avoidance travel by the steering operation of the driver or when the stability of vehicle behavior after obstacle avoidance is detected. The technology is disclosed.

JP 2000-302057 A

  According to the technique disclosed in Patent Document 1 described above, in the situation where the driver steers to avoid turning an obstacle, the avoidance ability can be improved. In the case of preventing a collision with an object, there is a problem that the braking distance, which is regarded as most important, cannot be shortened. By the way, as a technology for shortening the braking distance of a vehicle, ABS (Antilock Brake System) has been widely known and is mounted on many vehicles. However, this ABS is a longitudinal drive that can control the fastening torque between the front and rear shafts. When mounting on a four-wheel drive vehicle equipped with a force distribution control device, during braking, the front / rear driving force distribution control device reduces interference and eliminates interference between front and rear shafts to prevent interference with ABS. I am doing so. However, if the fastening torque between the front and rear shafts is reduced, torque transmission between the front and rear shafts cannot be performed, so the front and rear force of the four wheels cannot be utilized to the maximum. As a result, even if the ABS operates, the braking distance is shortened. There is a possibility that it cannot be done.

  The present invention has been made in view of the above circumstances. When the collision prevention control device generates an automatic brake and avoids a collision with an obstacle, the front and rear of the four wheels are considered in consideration of the operation of the ABS and the traveling state of the vehicle. An object of the present invention is to provide an integrated control device for a vehicle that is capable of stopping at a short braking distance by making the best use of force and having improved safety and reliability.

One aspect of the vehicle integrated control apparatus according to the present invention is a front obstacle information detecting means for detecting front obstacle information of the own vehicle, and the obstacle by determining the possibility of collision between the detected obstacle and the own vehicle. An integrated control apparatus for a vehicle, comprising: a collision prevention control means for generating a braking force for preventing a collision with an object; and a front / rear driving force distribution control means for controlling a fastening torque between front and rear shafts according to a motion state of the vehicle. The front / rear driving force distribution control means, when the collision prevention control means generates a braking force for preventing a collision with the obstacle, if the host vehicle is in a straight traveling state, until a preset time elapses. Sets the first fastening torque as the fastening torque, and then reduces the fastening torque to a second fastening torque close to substantially zero , while the collision prevention control means prevents a collision with the obstacle. Generate braking force When that, when the vehicle is in the turning state, to set to the second fastening torque without setting the first engaging torque as the fastening torque.

  According to the vehicle integrated control apparatus of the present invention, when the collision prevention control apparatus generates an automatic brake and avoids a collision with an obstacle, the front-rear force of the four wheels is considered while considering the operation of the ABS and the traveling state of the vehicle. It is possible to improve the safety and reliability by making the maximum use of the vehicle and stopping at a short braking distance.

It is explanatory drawing which shows schematic structure of the whole vehicle which concerns on one Embodiment of this invention. It is a flowchart of the collision prevention control program which concerns on one Embodiment of this invention. It is a flowchart of the integrated control program which concerns on one Embodiment of this invention. It is a flowchart of the control routine at the time of the collision prevention control action which concerns on one Embodiment of this invention. FIG. 5A is a characteristic diagram of a first delay time set by a steering wheel angle and a vehicle speed, and FIG. 5B is a graph showing a delay time characteristic according to an embodiment of the present invention. FIG. 5C is a characteristic diagram of the third delay time set by the vehicle body lateral acceleration and the vehicle speed.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
In FIG. 1, reference numeral 1 denotes an engine disposed in the front part of the vehicle, and the driving force of the engine 1 is transmitted from an automatic transmission device (including a torque converter and the like) 2 behind the engine 1 through a transmission output shaft 2a. It is transmitted to the transfer 3.

  Further, the driving force transmitted to the transfer 3 is input to the rear wheel final reduction device 7 via the rear drive shaft 4, the propeller shaft 5, and the drive pinion shaft portion 6, while the reduction drive gear 8, the reduction driven gear 9. Then, it is input to the front wheel final reduction gear 11 via the front drive shaft 10 which is the drive pinion shaft portion. Here, the automatic transmission 2, the transfer 3, the front wheel final reduction gear 11 and the like are integrally provided in the case 12.

  The driving force input to the rear wheel final reduction gear 7 is transmitted to the left rear wheel 14rl via the rear wheel left drive shaft 13rl and to the right rear wheel 14rr via the rear wheel right drive shaft 13rr. The driving force input to the front wheel final reduction gear 11 is transmitted to the left front wheel 14fl via the front wheel left drive shaft 13fl and to the right front wheel 14fr via the front wheel right drive shaft 13fr.

  The transfer 3 is a wet multi-plate clutch (transfer clutch) as a variable torque transmission capacity clutch in which a drive plate 15a provided on the reduction drive gear 8 side and a driven plate 15b provided on the rear drive shaft 4 side are alternately stacked. ) 15 and a transfer piston 16 that variably applies an engagement torque (transfer clutch torque) of the transfer clutch 15. Therefore, this vehicle controls the pressing force by the transfer piston 16 and controls the fastening torque of the transfer clutch 15 (transfer clutch torque), so that the torque distribution ratio between the front wheels and the rear wheels is, for example, 100: 0 to 50: It is a four-wheel drive vehicle with a front engine / front drive vehicle base (FF base) that can be varied between 50.

  The pressing force of the transfer piston 16 is given by a transfer clutch drive unit 41 configured by a hydraulic circuit having a plurality of solenoid valves and the like. A control signal (fastening torque Cawd between the front and rear shafts) for driving the transfer clutch drive unit 41 is output from a front and rear driving force distribution control device 40 described later.

  On the other hand, reference numeral 31 denotes a brake drive unit of the vehicle, and a master cylinder (not shown) connected to a brake pedal operated by a driver is connected to the brake drive unit 31. When the driver operates the brake pedal, the wheel cylinders of the four wheels 14fl, 14fr, 14rl, 14rr (the left front wheel cylinder 17fl, the right front wheel wheel cylinder 17fr, the left rear wheel wheel cylinder) are driven by the master cylinder through the brake drive unit 31. 17 rl, the right rear wheel wheel cylinder 17 rr) is introduced with brake pressure, thereby braking the four wheels.

  The brake drive unit 31 is a hydraulic unit provided with a pressurizing source, a pressure reducing valve, a pressure increasing valve, and the like. In addition to the brake operation by the driver described above, a collision prevention control device 30 described later, an ABS control device (not shown), etc. In response to this signal, the brake cylinders 17fl, 17fr, 17rl, and 17rr can be independently introduced with brake pressure.

  The vehicle is provided with each control device related to the integrated control of the image recognition device 20, the collision prevention control device 30, the front / rear driving force distribution control device 40, and the integrated control unit 50.

  Solid-state imaging such as a charge coupled device (CCD) that is attached to the image recognition device 20 in front of the ceiling in the vehicle interior with a certain interval, takes a stereo image of an object outside the vehicle from different viewpoints, and outputs the captured image information. Image information is input from a pair of left and right CCD cameras (stereo cameras) 21 using the elements, and the vehicle speed V is input from the vehicle speed sensor 62. Based on these information, the image recognition device 20 recognizes forward information such as three-dimensional object data and white line data in front of the own vehicle based on image information from the stereo camera 21, and automatically recognizes based on the recognition information and the like. Estimate the vehicle travel path. Further, the image recognition device 20 checks whether or not a three-dimensional object exists on the own vehicle traveling path, and if it exists, recognizes the latest one as an obstacle to be controlled by the anti-collision control by braking.

  Here, the image recognition apparatus 20 performs processing of image information from the stereo camera 21 as follows, for example. First, distance information is generated based on the principle of triangulation from a corresponding positional shift amount for a pair of stereo images obtained by capturing the traveling direction of the host vehicle with the stereo camera 21. Then, a well-known grouping process is performed on the distance information, and by comparing the grouped distance information with preset three-dimensional road shape data, solid object data, etc., white line data, road Sidewall data such as guardrails and curbs, and three-dimensional object data such as vehicles are extracted along the way. Furthermore, the image recognition device 20 estimates the own vehicle traveling path based on the white line data, the side wall data, the estimated traveling path of the own vehicle, etc., and performs the collision prevention control on the nearest three-dimensional object existing in front of the own vehicle traveling path. Extract (detect) as an obstacle to be controlled. When an obstacle is detected, as the obstacle information, the relative distance d between the own vehicle and the obstacle, the moving speed Vf of the obstacle (= (change ratio of the relative distance d) + the own vehicle speed V). ), Obstacle deceleration af (= differential value of obstacle moving speed Vf), lap ratio Rl in the width direction between the obstacle and the own vehicle (= the width of the own vehicle 1 overlaps the width of the obstacle) The ratio to the width of the vehicle 1) is calculated. Thus, in this embodiment, the image recognition apparatus 20 has a function as a front obstacle information detection means. In this embodiment, the detection of the front obstacle information is recognized based on the image information from the stereo camera 21. In addition, the detection is performed based on the image information from the monocular camera. You may do it.

  Then, the collision prevention control device 30 predicts whether or not there is a possibility of a collision between the host vehicle and the front obstacle according to a collision prevention control program described later until the host vehicle collides with the obstacle. Judgment is made based on time TTC (Time To Collision: a value obtained by dividing the relative distance d between the vehicle and the obstacle by the relative speed), and the predicted collision time TTC is shorter than the preset time Tca. If it is determined that there is a possibility, the brake is driven by setting a predetermined braking force (by referring to a predetermined value set in advance or a map corresponding to a preset vehicle speed V). To the unit 31. Thus, in the present embodiment, the collision prevention control device 30 is provided as a collision prevention control means. Note that the collision prevention control device 30 determines the possibility of collision between the host vehicle and the front obstacle in consideration of other methods such as the inter-vehicle distance, the inter-vehicle time, the lap ratio between the host vehicle and the obstacle, and the like. It may be determined.

The front / rear driving force distribution control device 40 receives the main transmission gear ratio i from the transmission control unit 61, the steering wheel angle θH from the steering wheel angle sensor 63, the yaw rate γ from the yaw rate sensor 64, and the lateral acceleration sensor 65. The vehicle body lateral acceleration (d ² y / dt ² ) is input, the accelerator opening θp is input from the accelerator opening sensor 66, the engine rotation speed ωe is input from the engine rotation sensor 67, and the integrated control unit 50 described later. A control signal (a switching signal for setting the fastening torque Cawd between the front and rear shafts) is input.

In the normal time, the front / rear driving force distribution control device 40 sets the fastening torque Cawd between the front and rear shafts according to the following equation (1) and outputs it to the transfer clutch drive unit 41. When the automatic brake by the collision prevention control device 30 is activated according to the control signal from 50, the fastening torque Cawd between the front and rear shafts is set to the value of the fastening torque set at the normal time or the fastening torque to be in the differential lock state. The value of the first engagement torque (first transfer clutch torque), which is a value, or the value of the second engagement torque (second transfer clutch torque) close to 0 is set to the transfer clutch drive unit 41. It is configured to output.
Cawd = (1 / (1 + Tawd · s)) · Fd · Gawd (1)
Here, Tawd is a time constant of a low-pass filter (first-order lag filter), s is a Laplace operator, and Gawd is a control gain (predetermined value). Fd is a transfer input torque and is calculated by, for example, the following equation (2).
Fd = f (θp, ωe) · (i · Gf) (2)
Here, f (θp, ωe) is an engine output torque estimated based on the accelerator opening θp and the engine speed ωe with reference to a preset map (engine characteristic map). Gf is a final gear ratio. The fastening torque Cawd between the front and rear shafts is not limited to that calculated by the above-described equation (1), and may be a value set by other map reference or calculation. Thus, the front / rear driving force distribution control device 40 is provided as a front / rear driving force distribution control means.

The integrated control unit 50 receives the vehicle speed V from the vehicle speed sensor 62, the handle angle θH from the handle angle sensor 63, the yaw rate γ from the yaw rate sensor 64, and the vehicle body lateral acceleration (d ² y from the lateral acceleration sensor 65. / Dt ² ) and a control signal (automatic brake operation / non-operation signal) is input from the collision prevention control device 30. Then, the integrated control unit 50, when the collision prevention control device 30 generates a braking force for preventing a collision with an obstacle according to the integrated control program described later, when the host vehicle is in a straight traveling state, The first transfer clutch torque is set as the engagement torque Cawd between the front and rear shafts until (delay time) Tde elapses, and thereafter, the engagement torque Cawd is reduced to the second transfer clutch torque close to approximately zero. Then, a control signal is output to the front / rear driving force distribution control device 40. When the host vehicle is turning, a control signal is output to the front / rear driving force distribution control device 40 so as to set the second transfer clutch torque.

Next, a collision prevention control program executed by the collision prevention control device 30 will be described with reference to the flowchart of FIG.
First, in step (hereinafter abbreviated as “S”) 101, it is determined whether or not an obstacle is detected by the image recognition device 20. TTC is calculated.

  Next, the process proceeds to S103, where the collision prediction time TTC is compared with a preset threshold value Tca, and when the collision prediction time TTC is shorter than the preset threshold value Tca (when TTC <Tca), It is determined that there is a high possibility that the obstacle and the host vehicle will collide with each other, and the process proceeds to S104 (by referring to a predetermined value or a map corresponding to the preset vehicle speed V). ) Set the braking force and output it to the brake drive unit 31.

  In S105, the automatic brake operation determination flag Fc for determining the automatic brake operation by the collision prevention control device 30 is set (Fc = 1) and the program is exited.

  On the other hand, if it is determined in S101 that no obstacle has been detected, or if the collision prediction time TTC is equal to or greater than the preset threshold Tca (TTC ≧ Tca) in S103, the obstacle and the host vehicle collide. If it is determined that there is a low possibility that the program will be performed, the process proceeds to S106, the automatic brake operation determination flag Fc is cleared (Fc = 0), and the program is exited.

Next, an integrated control program executed by the integrated control unit 50 will be described with reference to the flowchart of FIG.
First, in S201, it is determined whether or not the automatic brake operation determination flag Fc set by the collision prevention control device 30 is set (Fc = 1). If Fc = 1, automatic braking by the collision prevention control device 30 is performed. If it is activated, the process proceeds to S202, and the delay time Tde is set. In this embodiment, the delay time Tde is set according to the vehicle speed V, the steering wheel angle θH, the yaw rate γ, and the vehicle body lateral acceleration (d ² y / dt ² ), and is set in advance. A first delay time tθ (see FIG. 5A) set by the steering wheel angle θH and the vehicle speed V, and a second delay time tγ set by the preset yaw rate γ and the vehicle speed V (FIG. 5). (B)) and three delay times set in advance according to the vehicle body lateral acceleration (d ² y / dt ² ) and the vehicle speed V (see FIG. 5C). The shortest time is set by comparing tθ, tγ, and ty.

As will be described later, this delay time Tde is the value of the fastening torque Cawd between the front and rear shafts when the automatic brake is operated by the anti-collision control device 30 or the fastening torque that is set to the diff lock state. Since the time of the first transfer clutch torque, which is the value of the time, is increased, the possibility of the vehicle behavior becoming unstable increases as the vehicle speed V increases, so any of the three delay times tθ, tγ, ty In this characteristic, the delay times tθ, tγ, and ty are set to be shorter as the vehicle speed V is higher. Further, as shown in FIG. 5A, when the absolute value | θH | of the steering wheel angle is large, the possibility that the vehicle behavior becomes unstable increases. Therefore, the larger the absolute value | θH | The delay time tθ of 1 is set to be short. Further, as shown in FIG. 5B, since the increase in the absolute value | γ | of the yaw rate is considered to be turning, the larger the absolute value | γ | of the yaw rate, the shorter the second delay time tγ. It is set up. Similarly, as shown in FIG. 5C, the increase in the absolute value | d ² y / dt ² | of the vehicle body lateral acceleration is considered to be turning, so the absolute value of the vehicle body lateral acceleration | d ² y The third delay time ty is set shorter as / dt ² | becomes larger.

Thus, in the present embodiment, by adopting the minimum values of the set three delay times tθ, tγ, ty, it is possible to set the optimal delay time Tde while avoiding the state where the vehicle behavior becomes unstable. It has become. In this embodiment, the minimum value of the three delay times tθ, tγ, ty is set as the delay time Tde. However, depending on the characteristics of the vehicle, either two or any one of them is set. Alternatively, the delay time Tde may be set according to any combination of the vehicle speed V, the steering wheel angle θH, the yaw rate γ, and the vehicle body lateral acceleration (d ² y / dt ² ).

  After setting the delay time Tde in S202, the process proceeds to S203, where the front / rear driving force distribution control device 40 is caused to execute the collision prevention control operation time control, and the process exits the flowchart.

  On the other hand, if Fc = 0 in S201 and the automatic brake operation is not executed by the collision prevention control device 30, the process proceeds to S204, where the normal driving control is executed by the front / rear driving force distribution control device 40. Exit the flowchart.

  Next, the collision prevention control operation control routine executed by the front / rear driving force distribution control device 40 in response to the collision prevention control operation control signal in S203 described above will be described with reference to the flowchart of FIG.

First, in S301, it is determined whether or not the absolute value | θH | of the steering wheel angle is smaller than a preset low value θHC (| θH | <θHC). If | θH | <θHC, the process proceeds to S302. It is determined whether the absolute value | γ | of the yaw rate is smaller than a preset low value γc (| γ | <γc). If | γ | <γc, the process proceeds to S303, where It is determined whether or not the absolute value of acceleration | d ² y / dt ² | is smaller than a preset low value Gyc (| d ² y / dt ² | <Gyc), and | d ² y / dt ² If | <Gyc, the process proceeds to S304, and the vehicle is determined to be in a straight traveling state.

On the other hand, if | θH | ≧ θHC in S301, | γ | ≧ γc in S302, or | d ² y / dt ² | ≧ Gyc in S303, the process proceeds to S305 and the vehicle is determined to be in a turning state. .

  After determining the traveling state (straight-running state or turning state) of the vehicle in S304 or S305, the process proceeds to S306 to determine whether or not the vehicle is in a straight-ahead state.

  If the result of the determination in S306 is that the vehicle is traveling straight, the process proceeds to S307, where it is determined whether or not the delay time Tde has elapsed, and if the delay time Tde has not elapsed, the process proceeds to S308 and is set at the normal time. The first transfer clutch torque, which is the value of the engagement torque or the value of the engagement torque at which the differential lock state is established, is set as the transfer clutch torque, and is output to the transfer clutch drive unit 41.

If it is determined in S306 that the vehicle is not in a straight traveling state, or if it is determined in S307 that the delay time Tde has elapsed, the process proceeds to S309, and the second transfer clutch torque close to approximately 0 is transferred. As described above, the clutch torque is set and output to the transfer clutch drive unit 41. Thus, according to the embodiment of the present invention, when the collision prevention control device 30 generates the braking force for preventing the collision with the obstacle, When the host vehicle is in a straight traveling state, the first transfer clutch torque is set as the engagement torque Cawd between the front and rear axes until a preset time (delay time) Tde elapses. To a second transfer clutch torque close to. Further, when the host vehicle is turning, the second transfer clutch torque is set. For this reason, when a braking force is applied to prevent a collision with an obstacle, the braking force that maximizes the front / rear force of the four wheels by the fastening torque between the front and rear shafts by the first transfer clutch torque when traveling straight. After that, the fastening torque between the front and rear shafts can be reduced to the second transfer clutch torque to prepare for the operation of the ABS. Further, when the vehicle is in a turning state, it is possible to secure the trace performance using the second transfer clutch torque as the fastening torque. In this way, when the collision prevention control device 30 generates an automatic brake and avoids a collision with an obstacle, it is short by making full use of the front / rear force of the four wheels while considering the operation of the ABS and the running state of the vehicle. It is possible to stop at the braking distance and improve safety and reliability.

Further, the delay time Tde for setting the first transfer clutch torque as the fastening torque between the front and rear shafts is the first delay time tθ set by the steering wheel angle θH and the vehicle speed V, the first delay time set by the yaw rate γ and the vehicle speed V. Compared to the delay time tγ of 2, the vehicle body lateral acceleration (d ² y / dt ² ) and the third delay time ty set by the vehicle speed V, the shortest time is set. It is possible to shorten the braking distance by the collision prevention control device 30 while accurately avoiding the state where the vehicle becomes unstable.

DESCRIPTION OF SYMBOLS 1 Engine 2 Automatic transmission 3 Transfer 14fl, 14fr, 14rl, 14rr Wheel 15 Transfer clutch 20 Image recognition apparatus (front obstacle information detection means)
21 Stereo camera 30 Collision prevention control device (collision prevention control means)
31 Brake drive part 40 Front-rear driving force distribution control device (front-rear driving force distribution control means)
41 Transfer clutch drive unit 50 Integrated control unit 61 Transmission control unit 62 Vehicle speed sensor 63 Handle angle sensor 64 Yaw rate sensor 65 Lateral acceleration sensor 66 Accelerator opening sensor 67 Engine speed sensor

Claims (7)

Forward obstacle information detecting means for detecting forward obstacle information of the host vehicle;
Anti-collision control means for determining the possibility of collision between the detected obstacle and the host vehicle and generating a braking force to prevent collision with the obstacle;
In a vehicle integrated control device comprising front and rear driving force distribution control means for controlling a fastening torque between front and rear shafts according to the motion state of the vehicle,
The front / rear driving force distribution control means, when the collision prevention control means generates a braking force for preventing a collision with the obstacle, if the host vehicle is in a straight traveling state, until a preset time elapses. A first fastening torque is set as the fastening torque, and thereafter, the fastening torque is reduced to a second fastening torque that is substantially close to 0 , while the collision prevention control means prevents the collision with the obstacle. when generating power, when the vehicle is in the turning state, the integrated control of the vehicle, characterized in that you set to the second fastening torque without setting the first engaging torque as the fastening torque apparatus. The first fastening torque is one of a high fastening torque for connecting the front and rear shafts in a substantially locked state and a fastening torque by normal control executed by the front and rear driving force distribution control means. The vehicle integrated control device according to claim 1. 3. The vehicle integrated control apparatus according to claim 1 , wherein the preset time is set to a shorter time at least as the vehicle speed is higher . 4. The vehicle integrated control apparatus according to claim 1 , wherein the preset time is set to be shorter as at least the absolute value of the yaw rate is larger . The vehicle integrated control apparatus according to any one of claims 1 to 4 , wherein the preset time is set to be shorter as at least the absolute value of the lateral acceleration is larger . 6. The vehicle integrated control apparatus according to claim 1 , wherein the preset time is set to be shorter as at least the absolute value of the steering wheel angle is larger . 7. The vehicle integrated control apparatus according to claim 1, wherein the front obstacle information detecting unit recognizes an obstacle from an image captured by a camera .

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