JP2000339596A - Vehicle motion control device - Google Patents

Abstract

(57) [Problem] To provide a vehicle motion control device capable of appropriately performing avoidance traveling of an obstacle in consideration of the motion of a vehicle during a turning operation. A control characteristic changing unit (80) calculates a relative speed (Vr) between an own vehicle and an obstacle from a vehicle speed (V) and speed data of the obstacle.
And using the relative speed Vr and the estimated value of the road surface μ,
The turning radius (trajectory of the bumper corner of the own vehicle) R of the own vehicle is calculated based on the relative motion between the obstacle and the own vehicle. Further, a turning center position is obtained based on the turning radius R, and a distance R0 from the turning center position to the corner of the obstacle is obtained. Further, the distance R0
Is compared with the turning radius R. When R0 ² ≦ R ^2, it is determined that the collision of the obstacle cannot be avoided by extending the current operation, and the front and rear driving force distribution control unit 60 and the left and right driving force distribution control unit 65 are determined. , And outputs a control characteristic change instruction signal to the rear wheel steering control unit 70 and the braking force control unit 75 in order to improve the turning performance of the vehicle.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle motion control device which detects an obstacle around a vehicle and avoids collision with the obstacle.

[0002]

2. Description of the Related Art Conventionally, various vehicle control devices have been developed and put into practical use in order to improve the running performance of vehicles. A braking force control device that applies braking force to appropriate wheels during cornering to improve running stability based on the relationship between the forces acting on the vehicle during cornering, etc., after controlling the steering of the rear wheels according to the running state of the vehicle Wheel steering control device, left and right wheel differential limiting device that controls the differential limiting force between left and right wheels based on the running condition of the vehicle, front and rear by controlling the differential limiting force between front and rear wheels based on the running condition of the vehicle An example is a power distribution control device that performs predetermined torque distribution between wheels.

In recent years, radar, ultrasonic waves, laser radar, and the like have been used to detect obstacles to travel, and an image pickup device such as a camera mounted on a vehicle has taken an image of a target landscape outside the vehicle. A measurement technique for processing a captured image to detect an object such as another vehicle and a road shape and further obtain a distance to an object has been developed and put into practical use.

Various proposals have been made to improve traveling safety using the technology of recognizing the traveling environment of the vehicle and the technology of the control device of the vehicle. For example, Japanese Patent Application Laid-Open No. 7-21500 has been proposed. In the official gazette, the distance and relative speed between the vehicle and the obstacle are detected to determine the possibility of vehicle contact, and when it is determined that there is a possibility of contact, the brake pressure is automatically applied to each wheel. In an automatic brake control device for an automobile that controls the vehicle by braking, when a driver's steering operation is detected, the brake pressure is controlled for each wheel so as to increase the turning performance of the vehicle in the operation direction. Technology is disclosed, the brake control pressure for each wheel,
When the driver's steering operation is detected, and the vehicle and the obstacle are approaching each other, and it is determined that contact between the vehicle and the obstacle cannot be avoided only by braking the vehicle by controlling the brake pressure. Is disclosed.

[0005]

However, in the technique described in Japanese Patent Application Laid-Open No. 7-21500, the determination as to whether or not to avoid a collision with an obstacle is based on the linear distance between the vehicle and the obstacle. Therefore, the motion of the vehicle during the turning operation to avoid the obstacle is not considered, and the motion control thereof may be insufficient.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide a vehicle motion control device capable of appropriately performing obstacle avoidance traveling in consideration of the vehicle motion during a turning operation. I do.

[0007]

In order to solve the above-mentioned problems, a first vehicle motion control device according to the present invention comprises: an obstacle recognizing means for detecting and recognizing an obstacle ahead of a host vehicle; Vehicle behavior control means for controlling the behavior of the own vehicle, and determining whether or not to avoid the obstacle based on the relative motion between the obstacle and the own vehicle during the obstacle avoiding operation of the own vehicle, And control characteristic changing means for changing the control characteristics of the vehicle behavior control means to improve the turning performance of the own vehicle when it is determined that the obstacle cannot be avoided by the extension of.

In a second vehicle motion control device according to the present invention, in the first vehicle motion control device, the control characteristic changing means may change a turning radius of the own vehicle relative to the obstacle. When the distance from the turning center position of the own vehicle to the obstacle is calculated, and the distance from the turning center position to the obstacle is smaller than the turning radius. The turning characteristic of the own vehicle is improved by changing the control characteristics of the vehicle behavior control means.

A third vehicle motion control device according to the present invention is the second vehicle motion control device, wherein the control characteristic changing means includes: a relative speed between the own vehicle and the obstacle; The turning radius is calculated based on the road surface friction coefficient obtained based on the above.

A fourth vehicle motion control device according to the present invention is the second vehicle motion control device, wherein the control characteristic changing means is based on a relative speed between the own vehicle and the obstacle and a yaw rate. The turning radius is calculated.

A fifth vehicle motion control device according to the present invention is the second vehicle motion control device according to the second vehicle motion control device, wherein the control characteristic changing means is based on a relative speed between the own vehicle and the obstacle and a lateral acceleration. The turning radius is calculated.

According to a sixth vehicle motion control device of the present invention, in the second vehicle motion control device, the control characteristic changing means sets a minimum turning radius of the own vehicle to the turning radius. I do.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. The drawings relate to an embodiment of the present invention, and FIG. 1 is a schematic explanatory view of the entire vehicle motion control device, and FIG.
FIG. 3 is a functional block diagram of a control characteristic change instruction unit, FIG. 3 is a flowchart showing a control characteristic change instruction routine, and FIG. 4 is an explanatory diagram of collision avoidance determination.

In FIG. 1, reference numeral 1 denotes an engine disposed at a front portion of a vehicle.
An automatic transmission (including a torque converter and the like) 2 behind the engine 1 to a transmission output shaft 2a
Is transmitted to the center differential device 3 through
From the center differential device 3, the rear drive shaft 4, the propeller shaft 5, and the drive pinion 6 are input to the rear wheel final reduction gear 7, while the transfer drive gear 8, the transfer driven gear 9, and the drive pinion shaft are formed. Front drive shaft 10
Is input to the front-wheel final reduction gear 11 via the. Here, the automatic transmission 2, the center differential device 3, the front wheel final reduction gear 11, etc.
It is provided in the case 12 integrally.

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
The signal 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.

In the center differential device 3, a large-diameter first sun gear 15 is formed on the input-side transmission output shaft 2a, and the first sun gear 15 is connected to a small-diameter first pinion 16. The first gear train is formed by meshing.

A small-diameter second sun gear 17 is formed on the rear drive shaft 4 for outputting power to the rear wheels. The second sun gear 17 is connected to the large-diameter second pinion 1.
The second gear train is constituted by meshing with the gear train 8.

The first pinion 16 and the second pinion 18 are formed integrally with a pinion member 19,
A plurality (for example, three) of the pinion members 19 are rotatably supported on a fixed shaft provided on the carrier 20.

The transfer drive gear 8 is connected to the front end of the carrier 20 so as to output to the front wheels.

The transmission output shaft 2a is rotatably inserted into the carrier 20 from the front, and the rear drive shaft 4 is rotatably inserted from the rear. The sun gear 15 and the second sun gear 17 are stored. The first pinions 16 of the plurality of pinion members 19 correspond to the first pinions.
The second pinion 18 is meshed with the second sun gear 17.

Thus, the first sun gear 1 on the input side
5 through the first and second pinions 16 and 18 and the second sun gear 17 to one output side and the other through the carrier 20 of the first and second pinions 16 and 18. And a composite planetary gear without a ring gear.

The two output members of the center differential device 3, namely, the carrier 20 and the second
A hydraulic multi-plate clutch (transfer clutch) 21 as a variable-capacity transmission clutch controlled by a front-rear driving force distribution control unit 60 described later is provided between the sun gear 17 and the sun gear 17.

Here, when the transfer clutch 21 is released, the torque distribution by the center differential device 3 is output as it is, but when the transfer clutch 21 is completely pressed, the differential of the center differential device 3 is reduced. The torque distribution is stopped, and the front and rear connection state is established. In particular,
The pressing force (transfer torque) of the transfer clutch 21 is controlled by the front / rear driving force distribution control unit 60. For example, the front / rear 35: 6 where the reference torque distribution is rear wheel biased.
Assuming that the torque distribution ratio is 5, a torque distribution control (power distribution control) is performed between 35:65 and a torque distribution ratio obtained in a directly connected state, for example, 50:50.

The rear wheel final reduction gear 7 has a differential function between the left and right wheels and a power distribution function, and includes a bevel gear type differential mechanism 22, a gear mechanism 23 including a three-row gear, and
It is mainly composed of two sets of clutch mechanisms 24 and is housed integrally in a differential carrier 25.

The drive pinion 6 meshes with a final gear 27 provided on the outer periphery of a differential case 26 of the differential mechanism 22, and transmits the driving force distributed from the center differential device 3 to the rear wheels.

The differential mechanism 22 is a differential pinion (bevel gear) rotatably supported by a pinion shaft 28 fixed to a differential case 26.
29 and left and right side gears (bevel gears) 30L and 30R meshing with the gears 29L and 30R are accommodated in a differential case 26, and these side gears 30L and 30R
, End portions of rear wheel left and right drive shafts 13rl and 13rr are axially mounted in a differential case 26, respectively.

That is, in the differential mechanism section 22, the differential case 26 is rotated on the same axis as the side gears 30L and 30R by the rotation of the drive pinion 6,
The gear mechanism formed inside the differential case 26 performs a differential between the left and right wheels.

The gear mechanism 23 is divided into left and right parts with the differential mechanism 22 interposed therebetween, and a first gear 23z1 is fixed to the left wheel side of the differential case 26,
A second gear 23z2 and a third gear 23z3 are axially mounted on the rear wheel right drive shaft 13rr, and the first, second, and third gears 23z1, 23z2, and 23z3 are on the same rotation axis. It is arranged.

The first, second and third gears 23z1, 2
3z2 and 23z3 mesh with the fourth, fifth and sixth gears 23z4, 23z5 and 23z6 disposed on the same rotation axis, and the fourth, fifth and sixth gears 23z4, 23z5 and 23z6. A fourth gear 23z4 is axially mounted on the left-wheel-side end of the torque bypass shaft 31 disposed on the rotation shaft core.

A clutch mechanism 2 for executing power distribution between the right and left wheels is provided at the right wheel end of the torque bypass shaft 31.
4 is provided with a first differential control clutch 24a, and the torque bypass shaft 31 is connected to the first differential control clutch 24a via the first differential control clutch 24a.
1 is the clutch hub side, and the shaft side of the sixth gear 23z6 is the clutch drum side), and is freely connectable to the shaft of the sixth gear 23z6 disposed on the left side of the first differential control clutch 24a. .

Further, a second differential control clutch 24b of the clutch mechanism 24 is provided on the torque bypass shaft 31 at a position between the differential mechanism 22 and the fifth gear 23z5. 31 is provided on the right side of the second differential control clutch 24b via the second differential control clutch 24b (the torque bypass shaft 31 is defined as the clutch hub side and the shaft of the fifth gear 23z5 is defined as the clutch drum side). Fifth arranged gear 23z5
It can be connected to the shaft part.

Then, the first, second, third, fourth, fifth and fifth
Sixth gears 23z1, 23z2, 23z3, 23z4, 23z5,
23z6 each tooth number z1, z2, z3, z4, z
5, z6 are, for example, 82, 78, 86, 46, 50,
42 and the first and fourth gears 23z1, 23
Based on the gear train of z4 ((z4 / z1) = 0.56), the gear train of the second and fifth gears 23z2 and 23z5 ((z5
/Z2)=0.64) is the speed increase, the third and sixth gears 23z
A gear train of 3,23z6 ((z6 / z3) = 0.49) is a reduction gear train.

For this reason, when both the first and second differential control clutches 24a and 24b are not connected and operated, the driving force from the drive pinion 6 passes through the differential mechanism section 22 as it is and the rear left and right drive shafts 13rl and 13rl. 13rr, but the first differential control clutch 24
a, the driving force distributed to the rear wheel right drive shaft 13rr is partially changed by the third gear 23z3, the sixth gear 23z6, the first differential control clutch 24a,
The torque is returned to the differential case 26 through the torque bypass shaft 31, the fourth gear 23z4, and the first gear 23z1 in this order. As a result, the torque distribution of the left rear wheel 14rl is increased. Recovery is improved.

Conversely, the second differential control clutch 2
4b, the driving force transmitted from the drive pinion 6 to the differential case 26 is partially transmitted to the first gear 23z1, the fourth gear 23z4, the torque bypass shaft 31, and the second differential control clutch. 24
b, the fifth gear 23z5, and the second gear 23z2, in that order, by-passing to the rear wheel right drive shaft 13rr, the right rear wheel 14rr
Is increased, and if the vehicle is on a normal road surface μ, the left turning property of the vehicle is improved.

Reference numeral 33 denotes a rear wheel steering unit of the vehicle. The rear wheel steering section 33 is provided with a rear wheel steering motor 34, and the power from the rear wheel steering motor 34 is transmitted via a worm / worm wheel and a link mechanism, and the left rear wheel 14rl and the right rear The wheel 14rr is steered.

The vehicle motion control device for controlling the motion of the vehicle having the above configuration includes a front / rear driving force distribution control unit 60 for controlling the transfer clutch 21 via a transfer clutch drive unit 61 and a differential control clutch control unit 66 for controlling the differential force. Control clutch 24
right and left driving force distribution control unit 6 that controls the motors a and 24b
5, a rear wheel steering control unit 70 for controlling the rear wheel steering motor 34 through a rear wheel steering drive unit 71, and each wheel cylinder 32fl, 32
Braking force control unit 7 for controlling fr, 32rl, 32rr
5 as a vehicle behavior control unit, and a control characteristic change unit 80 for instructing each control unit to change the control characteristics as a control characteristic change instruction unit.

The vehicle is provided with sensors and switches for detecting the running state of the vehicle. That is, each wheel 14fl, 14fr, 14rl, 14rr
Wheel speed sensors 41fl, 41fr, 41rl,
The vehicle speed V is detected and detected as a predetermined value and input to the front and rear driving force distribution control unit 60, the left and right driving force distribution control unit 65, the rear wheel steering control unit 70, the braking force control unit 75, and the control characteristic changing unit 80. Is done. Also, handle angle θH
Is detected by the steering wheel angle sensor 42, and the yaw rate γ
Is detected by the yaw rate sensor 43, the front / rear driving force distribution control unit 60, the left / right driving force distribution control unit 65, the rear wheel steering control unit 70, the braking force control unit 75, and the control characteristic changing unit 8
Input to 0. Further, the lateral acceleration Gy is detected by the lateral acceleration sensor 44 and input to the longitudinal driving force distribution control unit 60 and the left and right driving force distribution control unit 65. Further, the throttle opening θth is detected by the throttle opening sensor 45, the gear position is detected by the inhibitor switch 46, the engine speed Ne is detected by the engine speed sensor 47, and is input to the front-rear driving force distribution control unit 60. Is done. Further, the rear wheel steering angle δr is detected by the rear wheel steering angle sensor 48 and is input to the rear wheel steering control unit 70. Further, the vehicle 1 is provided with an alarm lamp 55 on an instrument panel that is lit by the control characteristic changing unit 80 during avoidance traveling.

Further, an obstacle recognition system 90 for recognizing an obstacle ahead is mounted on the vehicle. The obstacle recognition system 90 includes a stereo optical system (not shown) composed of, for example, a pair of CCD cameras, and a three-dimensional distance distribution over the entire image based on the principle of triangulation from parallax of the obtained stereo image with respect to the same object. And an obstacle detection unit (not shown) for processing the distance distribution data, recognizing the road shape and a plurality of three-dimensional objects, and detecting an obstacle in front of the traveling road. Data relating to an obstacle in front (such as presence or absence of an obstacle, distance data (x, y) to the obstacle, speed data of the obstacle, etc.) is input to the control characteristic changing unit 80.

The above-described obstacle recognition is described in detail in Japanese Patent Application Laid-Open Nos. Hei 5-265545 and Hei 6-177236 previously filed by the present applicant. Here, the obstacle recognition system 90 is not limited to the one using the stereo optical system described above, but may be one using a laser, radar, laser radar, or the like.

Next, each of the above control units for controlling the behavior of the vehicle will be described.

In the front / rear driving force distribution control unit 60, for example, the lateral motion of the vehicle is determined by using the method disclosed by the present applicant in Japanese Patent Application Laid-Open No. Hei 8-2274, Based on the equation of motion, the cornering power of the front and rear wheels is extended to the nonlinear
Based on the ratio of the estimated cornering power of the front and rear wheels to the equivalent cornering power of the front and rear wheels on the road, the road surface friction coefficient μ is estimated according to the road surface condition. Then, the base clutch torque VTDout0 is determined by referring to a map set in advance in response to the road surface friction coefficient μ, and the input torque input to the center differential device 3 with respect to the base clutch torque VTDout0. Ti (calculated from engine speed Ne and gear ratio i), throttle opening θ
th, the actual yaw rate γ, the deviation between the target yaw rate γt calculated from the steering wheel angle θH and the vehicle speed V and the actual yaw rate γ (yaw rate deviation Δγ = γ−γt), and the lateral acceleration Gy. The control output torque VTDout which is the basis of the basic clutch engagement force FOtb of the distribution is calculated. Further, the control output torque VTDout is corrected by the steering wheel angle θ, determined as the steering wheel angle sensitive clutch torque as the basic clutch engagement force FOtb in the transfer clutch 21, and a predetermined signal corresponding thereto is transmitted to the transfer clutch drive unit 61. Then, the transfer clutch 21 is actuated to apply a differential limiting force to the center differential device 3 to perform power distribution control between the front and rear wheels.

Here, the correction based on the yaw rate deviation Δγ prevents the base clutch torque VTDout0 from over-steering or under-steering.
The clutch torque is added or reduced in accordance with the deviation between the actual yaw rate γ and the actual yaw rate γ.

For example, when turning, the target yaw rate γt
If the absolute value is large and the actual yaw rate γ (absolute value) is expected to be small and the vehicle is expected to understeer, the clutch torque is corrected to be reduced and the front and rear drive force distribution is adjusted to the rear wheels. It is corrected so as to improve the turning performance by making the weight uneven.

Conversely, when turning, the target yaw rate γ
If t (absolute value) is expected to be small and the actual yaw rate γ (absolute value) is expected to be large, and if the vehicle is expected to tend to oversteer, the clutch torque is corrected to increase and the driving force distribution before and after is increased. Correction is made so as to improve stability by making equal distribution in front and rear.

A signal for instructing a change in the control characteristics is input from the control characteristic changing unit 80 to the front-rear driving force distribution control unit 60. When the control characteristic change instruction signal for improving the turning performance is input to the front / rear driving force distribution control unit 60, the calculated target yaw rate γt (absolute value) is multiplied by a coefficient larger than 1 to obtain the target yaw rate γ.
t (absolute value) is corrected to be larger than usual, the clutch torque is corrected to be reduced, and the front and rear driving force distribution is rear-wheel biased, so that the turning performance is corrected.

The left / right driving force distribution control unit 65 calculates a clutch torque according to a ground contact load between the left and right of the vehicle based on, for example, the vehicle speed V, the steering wheel angle θH, and the lateral acceleration Gy, and converts the clutch torque to the steering wheel angle θH. In order to generate the final clutch torque by correcting the difference between the target yaw rate γt calculated from the vehicle speed V and the actual yaw rate γ, the first differential control clutch 24a or the second
The differential control clutch 24b is operated to execute power distribution control between the left and right wheels.

The correction based on the yaw rate deviation Δγ in the left and right driving force distribution control unit 65 also depends on the deviation between the target yaw rate γt and the actual yaw rate γ which are expected to occur during turning, in order to prevent the vehicle from over-steering or under-steering. Thus, the clutch torque is added or reduced.

For example, when turning, the target yaw rate γt
When it is expected that the (absolute value) is large and the actual yaw rate γ (absolute value) is small, and that the vehicle is expected to understeer, it is corrected so that the driving force distribution to the turning outer wheels is increased. Improve turning performance.

Conversely, when turning, the target yaw rate γ
When t (absolute value) is expected to be small and actual yaw rate γ (absolute value) is expected to be large, and when the vehicle is expected to tend to oversteer, an increase in the driving force distribution to the turning outer wheels is suppressed, Correct to improve stability.

The left / right driving force distribution control section 65 receives a signal from the control characteristic changing section 80 for instructing a change of the control characteristic. Then, when the control characteristic change instruction signal for improving the turning performance is input to the left and right driving force distribution control unit 65, the calculated target yaw rate γt (absolute value) is multiplied by a coefficient larger than 1 so that the target yaw rate γ
t (absolute value) is corrected to be larger than usual, and the driving force distribution of the turning outer wheel is corrected to be larger, so that the turning performance is improved.

The rear wheel steering control unit 70 controls the vehicle speed V,
Using the steering wheel angle θf and the yaw rate γ, a target rear wheel steering angle δr ′ is calculated based on a predetermined control law in advance, and the required rear wheel steering amount is set by comparing with the current rear wheel steering angle δr. A signal corresponding to the rear wheel steering amount is output to the rear wheel steering drive unit 71 to drive the rear wheel steering motor 33. Then, in accordance with a control signal from the control characteristic changing unit 80, a correction for setting a large in-phase steering amount of the rear wheel steering angle with respect to the front wheel steering angle and the yaw rate is performed in a predetermined manner.

The control performed by the rear wheel steering control unit 70 will be described in more detail. The control law set in the rear wheel steering control unit 70 is, for example, a known “steering wheel angle reverse phase” in the embodiment of the present invention. + Yaw rate in-phase control law "as a basic control law, and is given by the following equation (1).

Δr ′ = − kδ0 · f1 · (θH / N) + kγ0 · f2 · γ (1) where kδ0 is a steering wheel angle sensitive gain, kγ0 is a yaw rate sensitive gain, and N is a steering gear ratio.

The yaw rate sensitive gain kγ0 is a coefficient that determines the amount of steering of the rear wheels so as to decrease the yaw rate γ. Further, the steering wheel angle sensitive gain kδ0 is a coefficient that determines the amount of steering of the rear wheels so as to provide steering turning characteristics.

That is, the yaw rate sensitive gain kγ0 is given so as to steer the rear wheels in the same phase as the yaw rate γ, and the larger the yaw rate sensitive gain kγ0, the stronger the tendency of the vehicle to go obliquely without turning is increased. Generation of γ can be prevented. In other words, the vehicle characteristics have reduced turning characteristics and improved stability. As described above, the yaw rate sensitive gain kγ0 can be regarded as a coefficient indicating how much the steering amount should be given to the rear wheel with respect to the generated yaw rate γ to prevent the generation of the yaw rate γ.

However, the yaw rate sensitive gain kγ
If it is only 0, the vehicle cannot turn. To prevent this, a steering wheel angle sensitive gain kδ0 is set. That is, the turning characteristics of the vehicle are improved by steering the rear wheels in the opposite phase with respect to the steering wheel angle θH. Handle angle sensitive gain kδ for handle angle θH
The vehicle turns by setting the term of 0 to be larger. However, when the steering is returned to the neutral state, the control law includes only the term of the yaw rate sensitive gain kγ0, so that after turning, the rear wheels are steered in the direction of eliminating the yaw rate γ (the direction of eliminating the vehicle wobble). .

The steering wheel angle sensitive gain kδ0 is calculated based on the cornering power of the front wheels and the rear wheels.
When the vehicle speed is equal to or higher than a certain value, the value of the steering wheel angle sensitive gain kδ0 does not change. However, when the vehicle speed is close to 0, the steering wheel sensitivity gain kδ0
Is set to a small value.

With respect to the steering angle sensitive gain kδ0 and the yaw rate sensitive gain kγ0 set as described above,
In the embodiment of the present invention, by inputting a control characteristic change instruction signal from the control characteristic change unit 80, the steering wheel angle sensitive gain kδ0 can be corrected by multiplying by the rear wheel steering angle correction value f1. , Yaw rate sensitive gain k
γ0 can be corrected by multiplying by the rear wheel steering angle correction value f2.

That is, the steering wheel angle sensitive gain kδ0 is corrected by multiplying it by the rear wheel steering angle correction value f1 so that its absolute value becomes smaller. Steering is reduced so that turning performance of the vehicle is not improved.

Further, the yaw rate sensitive gain kγ0 is corrected to be larger than usual by multiplying by the rear wheel steering angle correction value f2, and the rear wheels are increased in phase with respect to the yaw rate γ so that the turning characteristic of the vehicle is improved. Is suppressed from being improved.

It is needless to say that the effect can be obtained even if only one of the correction of the steering wheel angle sensitive gain kδ0 and the correction of the yaw rate sensitive gain kγ0 is performed depending on the vehicle.

The braking force control unit 75 determines the wheel to be braked from the target yaw rate γt obtained from the vehicle speed V and the steering wheel angle θH and the actual yaw rate γ, and applies the calculated braking force, for example, to optimize the vehicle. Basically, a yaw moment is generated. Specifically, the target yaw rate γt
When the (absolute value) is large and the actual yaw rate γ (absolute value) is small and the vehicle tends to understeer, braking of the rear inner wheel in the turning direction is executed to improve the turning performance of the vehicle. Conversely, the target yaw rate γt (absolute value) is small,
When the actual yaw rate γ (absolute value) is large and the vehicle tends to oversteer, braking of the outer front wheel in the turning direction is executed to improve the stability of the vehicle.

Further, a signal for instructing a change in the control characteristics is input from the control characteristic changing unit 80 to the braking force control unit 75. When the control signal for improving the turning performance is input to the braking force control unit 75, the calculated target yaw rate γt (absolute value) is multiplied by a coefficient larger than 1, and the target yaw rate γt (absolute value) becomes larger than usual. Will be corrected.

The control characteristic changing unit 80 includes a road surface μ estimating unit 81 for estimating the road surface μ based on the running state of the vehicle, and an extension of the current operation based on the road surface μ, the vehicle speed and the obstacle data ahead. Collision avoidance determining unit 82 for determining whether collision avoidance between the vehicle and an obstacle is possible, and the collision avoidance determining unit 82
When it is determined that the collision avoidance of the own vehicle with the obstacle is impossible, the front / rear driving force distribution control unit 60, the left / right driving force distribution control unit 65,
A control characteristic change instruction unit 83 that outputs a control characteristic change instruction signal to the rear wheel steering control unit 70 and the braking force control unit 75 to improve the turning performance of the vehicle. When it is determined that collision avoidance with an object is impossible, for example, an alarm driving unit 84 that drives an alarm lamp 55;
It is provided with.

The road surface μ estimating section 81 calculates the steering wheel angle θ.
H, lateral acceleration Gy, yaw rate γ, and vehicle speed V are input,
For example, a high μ road reference body slip angle βH and a low μ road reference body slip angle βL are calculated by a vehicle motion model based on a vehicle motion equation based on the handle angle θH and the vehicle speed V. Based on the lateral acceleration Gy, the yaw rate γ, the high μ road reference vehicle slip angle βH, and the low μ road reference vehicle slip angle βL, the estimated vehicle slip angle β is calculated by the observer using a vehicle motion model while feeding back the actual vehicle behavior. Then, based on the high μ road reference vehicle slip angle βH, the low μ road reference vehicle slip angle βL, and the estimated vehicle slip angle β, a road surface friction coefficient μ estimated based on a relationship between preset vehicle slip angles is calculated. It has become. The method of estimating the road surface μ is described in detail in Japanese Patent Application No. 10-242030 previously filed by the present applicant.

The collision avoidance judging section 82 calculates the vehicle speed V, data on the obstacle ahead (the presence or absence of an obstacle, distance data (x, y) from the obstacle, speed data of the obstacle, etc.), and the estimated value of the road surface μ. The turning radius R of the own vehicle relative to the obstacle is calculated based on the relative motion between the obstacle and the own vehicle, and the obstacle R is calculated from the turning radius R and the turning center position of the own vehicle. By comparing with the distance R0 to the corner, it is determined whether or not an obstacle ahead of the vehicle can be avoided by extending the current operation.

Specifically, as shown in FIG. 4, the collision avoidance judging section 82 first obtains the relative speed Vr between the own vehicle and the obstacle from the vehicle speed V and the speed data of the obstacle. Using this relative speed Vr and the estimated value of the road surface μ, the turning radius (trajectory of the bumper corner of the own vehicle) R of the own vehicle based on the relative motion between the obstacle and the own vehicle is calculated (that is, the obstacle). The turning radius R of the own vehicle in the system where is stationary is calculated).

R = Vr ² / μ · g + W / 2 (2) g: Gravitational acceleration (m / s ² ) Next, the collision avoidance determination unit 82 sets the own vehicle position as the origin based on the turning radius R. Turning center position (0, y0)
Ask for.

Here, y0 = R−w / 2 (3) w: Vehicle width of the own vehicle Next, the collision avoidance determining unit 82 calculates the turning center position (0, y0) and the coordinates of the corner of the obstacle. (Xt, yt), the distance R0 from the turning center position of the own vehicle to the corner of the obstacle.
Ask for.

R 0 ² = xt ² + (yt−y 0) ² (4) Next, the collision avoidance determination unit 82 calculates the obtained R and R
Based on 0, it is determined whether or not a collision with an obstacle can be avoided by extending the current operation. In this case, the condition that the collision of the obstacle cannot be avoided by extending the current operation is as follows: R0 ² ≦ R ² (5) The result of this determination is output to the control characteristic change instructing section 82.

When the collision avoidance judging section 82 judges that the collision with the obstacle cannot be avoided by extending the current operation, the control characteristic change instructing section 82 gives the control section a turning characteristic of the vehicle. And outputs a control characteristic change instruction signal to improve the control characteristic.

In this case, when the control characteristic change instruction signal is input, the front / rear driving force distribution control unit 60, the left / right driving force distribution control unit 65, and the braking force control unit 75 reduce the calculated target yaw rate γt (absolute value). The target yaw rate γt (absolute value) is corrected to be larger than usual by multiplying by a coefficient larger than 1, thereby improving the turning performance of the vehicle. Further, in the rear wheel steering control unit 70, when the control characteristic change instruction signal is input, the rear wheel steering angle correction values f1 and f2 are changed, and the steering amount of the rear wheels to the opposite phase is increased and corrected. Thus, the turning performance of the vehicle is improved.

Next, a vehicle characteristic changing routine by the control characteristic changing unit 80 will be described with reference to a flowchart shown in FIG. This routine is executed at predetermined time intervals. First, step (hereinafter abbreviated as “S”) 1
In step 01, the control characteristic changing unit 80 checks whether or not the control characteristic is being changed. If the control characteristic is being changed, the routine exits from the routine.

On the other hand, at S101, the control characteristic changing unit 80
If it is determined that the control characteristic is not being changed, the process proceeds to S102, and the obstacle recognition system 90 sends data on the forward obstacle (the presence / absence of an obstacle, the distance data (x,
y), speed data of an obstacle, etc.), and then proceeds to S103.

In S103, the collision avoidance determination unit 82 checks whether there is an obstacle (including a preceding vehicle) ahead of the own vehicle based on the data obtained from the obstacle recognition system 90. If there is no obstacle, the process directly exits the routine. If there is an obstacle, the process proceeds to S104.

In S104, the steering wheel angle sensor 42
, The yaw rate γ from the yaw rate sensor 43, the lateral acceleration Gy from the lateral acceleration sensor 44,
A sensor value such as a vehicle speed V based on each wheel speed from the wheel speed sensors 41fl, 41fr, 41rl, 41rr is input, and S10 is performed.
The program proceeds to step 5, where the road surface μ estimating section 82 estimates the road surface friction coefficient μ based on the steering wheel angle θH, the yaw rate γ, the lateral acceleration Gy, and the vehicle speed V.

Next, the process proceeds to S106, where the collision avoidance determination section 82 obtains the relative speed Vr between the host vehicle and the obstacle based on the speed data of the obstacle and the vehicle speed V.
The turning radius R of the own vehicle is obtained based on the road surface μ estimated value.
Further, in S106, the turning center position (0, y0) of the own vehicle is obtained based on the turning radius R, and then S107.
Proceed to.

In step S107, a distance R0 from the turning center position of the vehicle to the obstacle corner is obtained based on the turning center position (0, y0) and the coordinates (xt, yt) of the obstacle corner. Compare R0 with turning radius R. And
Comparing the turning radius R and the distance R0, in the case of R0 ^2> R ^2, the process exits the routine determines that avoids obstacles in the extension of the current operation.

[0079] On the other hand, in the S107, R0 ² when a ≦ R ² is a prolongation of the current operation proceeds to S108 and determines that it can not avoid the obstacle, the driving force distribution before and after via the control characteristics changing instruction section 83 A control characteristic change instruction signal is output to the control unit 60, the left and right driving force distribution control unit 65, the rear wheel steering control unit 70, and the braking force control unit 75 to improve the turning performance of the vehicle. After driving the alarm lamp 55 through the section 84, the routine exits.

According to this embodiment, the accuracy of the determination as to whether or not to avoid an obstacle is improved by taking into account the lateral movement of the vehicle in addition to the distance information to the obstacle in front of the vehicle. Vehicle motion control and alarm control can be performed.

That is, the road surface friction coefficient μ is estimated based on the lateral movement (lateral acceleration Gy and yaw rate γ), and the turning radius R of the vehicle is calculated using the estimated road surface μ value and the relative speed Vr of the obstacle. Is calculated, and whether or not to avoid an obstacle is determined using the turning radius R. Therefore, the determination becomes accurate, and appropriate vehicle motion control and alarm control can be performed.

The turning radius R and the distance R0 from the turning center position to the obstacle at the time of determining whether or not to avoid the obstacle are:
Since it is obtained by a simple calculation, the control is simple and accurate.

Here, in the above embodiment, the turning radius R of the own vehicle is calculated based on the relative speed Vr with respect to the obstacle and the estimated value of the road surface μ. However, the calculation may be performed by the following method. good.

R = Vr / γ + W / 2 (6) γ: yaw rate (rad / s) R = Vr ² / Gy + W / 2 (5) Gy: lateral acceleration (m / s ² ) The minimum turning radius may be set.

Of course, when the turning radius of the own vehicle is obtained by such a method, the same effects as those described above can be obtained.

[0086]

As described above, according to the present invention, it is possible to provide a vehicle motion control device capable of appropriately performing an obstacle avoidance run in consideration of the motion of the vehicle during a turning operation.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory diagram of an entire vehicle motion control device.

FIG. 2 is a functional block diagram of a control characteristic change instruction unit.

FIG. 3 is a flowchart showing a control characteristic change instruction routine.

FIG. 4 is an explanatory diagram of collision avoidance determination.

[Explanation of symbols]

41 fl, 41 fr, 41 rl, 41 rr Wheel speed sensor 42 Handle angle sensor 43 Yaw rate sensor 44 Throttle opening sensor 46 Inhibitor switch 47 Engine speed sensor 48 Rear wheel steering angle sensor 60 Front / rear driving force distribution control Section (vehicle behavior control means) 65 left / right driving force distribution control section (vehicle behavior control means) 70 rear wheel steering control section (vehicle behavior control means) 75 braking force control section (vehicle behavior control means) 80 control characteristics Change part (control characteristic changing means) 90 ... Obstacle recognition system (obstacle recognition means)

Claims (6)

[Claims] 1. An obstacle recognizing means for detecting and recognizing an obstacle in front of an own vehicle, a vehicle behavior control means for controlling a behavior of the own vehicle in accordance with a traveling state, and an obstacle avoiding operation of the own vehicle. It determines whether or not to avoid the obstacle based on the relative motion between the obstacle and the own vehicle, and changes the control characteristics of the vehicle behavior control means when it is determined that the obstacle cannot be avoided by extending the current operation. And control characteristic changing means for improving the turning performance of the vehicle. 2. The control characteristic changing means calculates a turning radius of the own vehicle relative to the obstacle based on the movement of the own vehicle and the obstacle, and calculates the turning radius of the own vehicle from the turning center position of the own vehicle. Calculating the distance to the obstacle, and changing the control characteristic of the vehicle behavior control means to improve the turning performance of the own vehicle when the distance from the turning center position to the obstacle is smaller than the turning radius. A vehicle motion control device characterized by the above-mentioned. 3. The control characteristic changing means calculates the turning radius based on a relative speed between the own vehicle and the obstacle and a road surface friction coefficient obtained based on a running condition of the own vehicle. The vehicle motion control device according to claim 2, wherein 4. The vehicle motion control device according to claim 2, wherein the control characteristic changing means calculates the turning radius based on a relative speed between the own vehicle and the obstacle and a yaw rate. . 5. The vehicle motion control device according to claim 2, wherein the control characteristic changing means calculates the turning radius based on a relative speed between the own vehicle and the obstacle and a lateral acceleration. . 6. The vehicle motion control device according to claim 2, wherein the control characteristic changing means sets a minimum turning radius of the own vehicle to the turning radius.