JP2000177617A - Control device for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To more safely perform the automatic steering in turning by controlling a driving force regulating means to reduce the driving force of a vehicle. SOLUTION: The reduction quantity of driving force is calculated on the basis of the expression: ΔTH=K.(Ftmax-(Ft+α)) (Q23). In the expression, K is a control constant, and Ftmax is the maximum value of actual transverse force Ft. The driving force reduction quantity ΔTH is calculated so as to be larger as the deviation obtained by subtracting Ff+α from Ftmax is larger. After this calculation (Q23), it is judged whether the reduction quantity ΔTH is smaller than 0 or not (Q26). When the result of this judgment is YES, the reduction quantity ΔTH is added to the present throttle opening TH to calculate the throttle opening TH (Q27). When the acceleration demand from a driver is inputted, the increase correction quantity ΔTH1 of the throttle opening is calculated (Q30). Thereafter, the increase correction quantity ΔTH1 is added to the throttle opening TH to calculate the throttle opening TH at this time (Q31).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for a vehicle which performs automatic steering.

[0002]

2. Description of the Related Art In recent vehicles, for driver assistance,
One that performs automatic steering along a traveling lane has been proposed. Japanese Unexamined Patent Publication No. Hei 9-142327 proposes an automatic steering system that performs a braking operation and a reduction in engine output in order to lower the turning level when the vehicle is turning close to the vehicle performance limit.

[0003]

By the way, in performing the automatic steering, it is a precondition that the direction of the vehicle is changed or turned (the control target value of the automatic steering is realized) as the automatic steering is performed. Becomes On the other hand, in the case of automatic steering, since the steering is performed irrespective of the driver's steering intention, safety is more sufficiently secured during automatic steering than when the driver is manually steering. It is desired. That is, as described in the above-mentioned publication, performing automatic steering near the limit of the kinetic performance of the vehicle is not preferable in terms of safety, particularly in automatic steering that is intervened to prevent the vehicle from falling into an inappropriate state due to manual steering. It will be.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a vehicle control device capable of performing safer automatic steering, particularly automatic steering during turning. It is in.

[0005]

In order to achieve the above-mentioned object, the present invention adopts the following solution. That is, as set forth in claim 1 of the claims, in a vehicle control device that performs automatic steering control with a steering control target value determined to travel along a traveling lane, A driving force adjusting means for adjusting the driving force of the vehicle, and a target lateral force determining a lateral force required to secure the turning by the automatic steering control as a target lateral force based on a driving state of the vehicle related to the turning. Means, an actual lateral force determining means for determining a lateral force that can be actually secured based on the running state of the vehicle, and an actual lateral force determined by the actual lateral force determining means being equal to the target lateral force by a predetermined amount. And a driving force control means for controlling the driving force adjusting means so as to be greater than a value obtained by adding the marginal lateral force to reduce the driving force of the vehicle. Preferred embodiments on the premise of the above solution are as described in claim 2 and the following claims.

[0006]

According to the first aspect of the present invention, it is ensured that the actual lateral force is larger than the target lateral force required for the turning based on the automatic steering by a predetermined marginal lateral force. It is turned with a margin, which is very preferable for safety.

According to the second aspect, the marginal lateral force is set as a more optimal value by correction, which is preferable for satisfying both safety and traveling performance at a high level. According to the third aspect, a slow-in / fast-out which is considered to be preferable at the time of cornering is performed, and the vehicle quickly escapes from the corner while safely entering the corner to satisfy the acceleration performance near the end of the turn. be able to. According to the fourth aspect, the marginal lateral force (the basic value thereof) is increased as the deviation amount from the traveling lane where the degree of automatic steering is increased is increased, which is extremely preferable in terms of safety.

According to the fifth aspect, both quick turning and safe turning can be satisfied at a high level according to the quality of the field of view. According to the sixth aspect, it is preferable to safely perform turning by automatic steering at nighttime when visibility is poor. According to claim 7, it is preferable to safely perform turning by automatic steering in rainy weather when visibility is poor. According to the eighth aspect, the excess lateral force is corrected according to the size of the lane width, which indicates the magnitude of the margin of the lane departure, so that both a quick turn and a safe turn are satisfied at a high level. be able to. According to claim 9,
The driver's aggressive acceleration demand can be satisfied.

According to the tenth aspect, it is possible to satisfy the driver's will to actively secure safety. According to the eleventh aspect, both quick turning and safe turning can be satisfied at a high level in response to a change in turning radius. According to the twelfth aspect, while sufficiently securing the safety at the beginning of turning when the behavior change of the vehicle in the unstable direction becomes large,
A quick turn in the middle of turning and a sufficient acceleration from the latter half of the turn can be satisfied at a high level.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1, reference numeral 1 denotes a vehicle (automobile), which is an FF vehicle in the embodiment. The traveling lane is indicated by reference numeral 2 and its left boundary line (white line) is indicated by reference numeral 2.
L and the right border is denoted by 2R. Although not shown in the actual traveling lane 2, the center line of the traveling lane 2 is indicated by a dashed line and is denoted by reference numeral 2C. The vehicle 1 is automatically steered with the center line 2C as a target trajectory. In FIG. 1, the vehicle 1 is slightly deflected to the right with respect to the center line 2C, and the front of the vehicle body is slightly inclined to the right. Is shown. In the state shown in FIG. 1, during automatic steering, a steering force is applied so that left and right front wheels 3 as steered wheels face left, and a steering handle 4 as a steering unit is provided.
To the steering wheel 4 (the direction of the reaction force applied to the steering wheel 4 is the right direction opposite to the left direction in which the steered wheels 3 are steered).

FIG. 2 shows a steering system and a control system of the vehicle 1. In FIG. 2, left and right front wheels 3 as steering wheels are mechanically connected to each other via a pair of left and right knuckle arms 11, a pair of left and right tie rods 12, and a drive mechanism (reduction gear mechanism) 13 connecting the left and right tie rods 12. Are linked together. Each of the above components 11, 12, 13
However, a driving mechanism 13 is provided with a motor (actuator) 14 as a steering force applying means. The steering wheel 4 is configured independently of the steering mechanisms 11 to 13, and a motor 15 as a steering reaction applying means is provided for a steering shaft 4 a attached to the steering wheel 4.

At the time of automatic steering, as will be described in detail later, a steering torque (steering force) is applied to the left and right front wheels 3 by a motor 14, while a steering wheel 4 is provided by a motor 15.
, A steering reaction force is applied. At the time of normal manual steering which is not automatic steering, that is, at the time of steering accompanying manual operation of the steering wheel 4 by the driver, the motor 14 is driven according to the steering amount or steering torque of the steering wheel 4 and the operating direction of the steering wheel 4 is changed. The front wheel 3 is steered, and a steering reaction force corresponding to the steering amount or the steering torque is generated by the motor 15.
Given by

The motors 14 and 15 are controlled by a controller U constructed using a microcomputer. As shown in FIG. 3, signals from various sensors and switches are input to the controller U.
The following various states are detected (or calculated). The various states detected (or calculated) are as follows. First, the position of the center line 2C of the traveling lane 2 as the target trajectory is detected as yc using, for example, a camera mounted on the vehicle 1. The current lateral deviation between the center line 2C in the front-rear direction and the center line 2C of the vehicle 1 is detected as yo using the camera, for example. The current vehicle speed is detected as v by the vehicle speed sensor. The yaw angle of the vehicle 1 is detected as yw using the camera, for example. The steering amount (actual steering amount of the front wheels 3) is detected as θ by the steering angle sensor. The curvature of the traveling lane 2 is determined by using the camera or the navigation system, a beacon for receiving a signal from a road information transmitting device attached along the road surface, and a magnetic nail indicating road information embedded in the road surface. Is detected. Automatic transmission EA for vehicles
T) A signal indicating the current gear stage of 22; a signal indicating the operating state of the brake switch; a signal indicating the operating state of the headlight switch; a signal indicating the lane width (using the above camera)
Is entered. In addition, as the detection method of the above various states, a conventionally known appropriate method can be adopted.

In order to perform automatic steering so as to travel along the center line 2C as the target trajectory, the future lateral deviation y1 after T seconds is determined. The future lateral deviation amount y1 is represented by T, where T is a headway time that is a time predicted to take until the vehicle 1 reaches the forward fixation point P (see FIG. 1).
The center line position yc after second, the current lateral deviation amount yo,
It is calculated by the following equation 1 based on the headway time T, the vehicle speed v, and the yaw angle yw.

Y1 = yc− (yo + T × v × yw) (1)

At the time of automatic steering, a steering torque T2 as a first control target value for determining a steering force and a steering torque T1 as a second control target value for determining a steering reaction force.
Are determined based on the future lateral deviation amount y1 as shown in FIG. The steering torque T2 is always set to a value larger than the steering torque T1.
It is set to increase as the steering torque T2 increases. Further, each of the torques T1 and T2 is set to increase as the future lateral deviation amount y1 increases, but an upper limit value is also set.

FIG. 4 shows a map in which the torque T1 and T2 are prepared and stored in advance by mapping using the future lateral deviation amount y1 as a parameter.
Can be used to calculate the torques T1 and T2 based on y1. That is, for example, the calculation can be performed as T1 = k1 × y1, and the calculation can be performed as T2 = k2 × y1 (k1 and k2 are control constants, and k1 <k2). The output of the steering torque T2 to the motor 14 is the steering reaction force T
It is preferable to delay the output to one motor 15 by a predetermined amount t, and the degree of this delay (delay time) t can be changed according to the running state.

The controller U controls the automatic steering so that the vehicle travels along the traveling lane. In addition, the controller U changes the direction of the vehicle according to the automatic steering and safely performs the automatic steering. Driving force control (control of the torque applied to the driving wheels) is performed, and for this purpose, the throttle actuator 21 for opening and closing the throttle valve of the engine is also controlled. Further, in order to prevent the vehicle from entering a curve at an overspeed, a shift control of the automatic transmission is also performed.

The basic control contents of the controller U are as follows. That is, the target lateral force Ff required to realize the automatic steering and the lateral force Ft that can be actually secured.
And the marginal lateral force α are determined (estimated), and the throttle actuator 21 is adjusted so as to satisfy the relationship of Ft> Ff + α.
(If Ft ≦ Ff + α, control is performed to suggest the throttle opening). The lateral force indicates the lateral grip force of the tire, and any value related to the lateral grip force can be appropriately used as the lateral force. The marginal lateral force α is appropriately corrected so that safe turning by automatic steering and quick turning are both satisfied at a high level.

As shown in FIG. 3, the target lateral force Ft described above is obtained.
Is determined based on the target locus (target turning locus) and the vehicle speed. The side slip angle of the vehicle is estimated based on the vehicle speed and the steering angle, and the actual driving force is calculated from the engine speed, the throttle opening, and the current gear position, and the actual driving force is calculated from the lateral slip angle and the actual driving force. Then, the actual lateral force (the maximum lateral force that can be secured) Ft is calculated (using a friction circle indicating the relationship between the longitudinal grip force and the lateral grip force of the tire).

The above-mentioned marginal lateral force α is basically determined on the basis of the above-mentioned future deviation y1, and α is set to be larger as y1 is larger. Then, the basic marginal lateral force α determined based on y1 is corrected according to the presence or absence of the brake operation, the presence or absence of the headlight lighting, the size of the lane width, the change in the curvature of the target locus, and the like.

As the control before the curve, two thresholds F1 and F2 indicating the lateral force are set (F1 <F2) to prevent the curve from entering at a dangerous speed. That is, when the target lateral force Ff is larger than the first threshold value F1 before the first predetermined time t1 second before entering the curve, the throttle valve is fully closed. Further, if the target lateral force Ff is larger than the second threshold value F2 before the second predetermined time t2 seconds before entering the curve (t1> t2), the automatic transmission is shifted down by one stage. Such a throttle valve fully-closed control and a shift-down control prevent the vehicle from entering a curve at a dangerous speed.

Next, the control contents of the controller U will be described in detail with reference to the flowcharts of FIGS. 5 to 7. In the following description, Q indicates a step. First, Q in FIG.
After inputting (calculating) the various data shown in FIG. 3 at 1, the future lateral deviation amount y1 is calculated at Q2 as described above. In Q3, based on the future lateral deviation amount y1, the steering torque T2 (steering reaction force T
1) is determined. In Q4, the marginal lateral force α is determined based on the future lateral deviation amount y1.

In Q5, the marginal lateral force α is corrected in accordance with the equation shown here, using the lane width W and d indicating headlight on / off as parameters. That is, α is corrected so as to decrease as the lane width W increases, and d is set to a predetermined positive value when the headlight is turned on, and d is set to 0 when the headlight is not turned on (when the headlight is turned on). , The marginal lateral force α is increased as compared with the non-lighting state.)

In Q6 to Q10, the estimation of the sideslip angle, the estimation of the actual driving force, the estimation of the actual lateral force, the estimation of the curvature R of the road, and the estimation of the target lateral force Ff are sequentially performed. After Q10, the process proceeds to Q21 in FIG. In this Q21, it is determined whether the vehicle is currently traveling at the entrance of the curve or the vehicle is turning normally. If the determination in Q21 is YES, in Q22, it is determined whether or not the change rate of the reciprocal of the curvature R (the radius of curvature) is 0 or more, that is, whether or not the road is in a direction in which the degree of curve is sharp. . This Q23
If the determination is YES, the process shifts to Q23.

If the determination in Q21 is NO, or if the determination in Q22 is NO, the process shifts to Q24 to determine whether or not the vehicle is in a dangerous driving state. Specifically, in Q24, it is determined whether or not the brake is being turned on. In the determination of Q24, Y
In the case of ES, the process directly proceeds to Q23, and in the case of NO in the determination of Q24, the marginal lateral force α is corrected to a small value in Q25. This correction of Q25 is performed based on the ratio between the maximum curvature Rmax in the curve and the curvature R of the currently running curve portion (correction in the direction of decreasing α). After Q25, the process proceeds to Q23.

In Q23, the reduction amount of the driving force (the reduction amount of the throttle opening ΔTH) is calculated based on the equation shown here. In the equation, k is a control constant (control gain), and Ft
max is the maximum value of the actual lateral force Ft (actually, Q8
Is the maximum value that can be taken, and Ft = Ftmax). As is apparent from this equation, the driving force reduction amount ΔTH is calculated by subtracting “Ff +
It is calculated so that the larger the deviation obtained by subtracting “α” becomes, the larger the deviation becomes. After Q23, in Q24, the reduction amount TH
Is smaller than 0. If the determination in Q26 is YES, in Q27, the current throttle opening TH is added with the reduction amount ΔTH to calculate the current throttle opening TH (reduction in throttle opening).

After Q27 or in the determination of Q26, NO
Respectively, in Q28, the accelerator opening AC
Is greater than or equal to a predetermined value a. If the determination in Q28 is YES, the accelerator opening A
It is determined whether or not the rate of change △ AC of the accelerator opening obtained by differentiating C is equal to or greater than a predetermined value b. If the determination in Q29 is YES, it is determined that there is a request for acceleration by the driver, and in Q30, the increase correction amount ΔTH1 of the throttle opening is calculated according to the equation shown here. Thereafter, in Q31, the current throttle opening TH is calculated by adding the increase correction amount ΔTH1 to the throttle opening TH.

If NO in Q28 or Q2
If the determination in Step 9 is NO, the return is made without passing through Q30 and Q31. The throttle opening TH (target throttle opening) set in Q27 or Q31 can be realized, for example, at the timing after the return after Q31 and before the return, or by interrupt processing every predetermined time. (The same applies to the realization of the steering torque set in Q5).

FIG. 7 is a flow chart showing the contents of control for preventing a situation in which the vehicle enters the curve at an overspeed, and is for performing throttle full-close control and shift-down control. It is. That is, Q41
It is determined whether or not it is t1 seconds before the curve, and if the determination in Q41 is YES, it is determined in Q42 whether or not the target lateral force Ff is larger than the threshold value F1. . If the determination in Q42 is YES, Q
At 43, the throttle valve is fully closed. After Q43, or when NO is determined in Q41, furthermore, Q4
If the determination in step 2 is NO, it is determined in step Q44 whether or not t2 seconds before the curve is reached.
If the determination in 44 is YES, in Q45, it is determined whether or not the target lateral force Ff is greater than the threshold value F2. If the determination in Q45 is YES, a downshift is performed in Q46. When the determination in Q44 is NO, or when the determination in Q45 is NO, each is returned.

Although the embodiment has been described above, the present invention is not limited to this, and includes, for example, the following case. The automatic steering for following the target trajectory also includes a case where automatic steering is performed so as to return to the target trajectory only when the target trajectory deviates by a predetermined amount or more. The automatic steering is not limited to the case where the steered wheels 3 are actually steered, but also includes the case where only a steering reaction force is applied in order to encourage the driver to steer.

The actual lateral force Ft can be determined by using the road surface μ (the road surface friction coefficient) as a parameter. Also,
The extra lateral force α can be corrected by the road surface μ (the smaller the road surface μ, the larger α is set). Q21 to Q
25 corresponds to control for correcting the marginal lateral force α in the latter half of the turn to a small value. For example, the navigation system is used to detect that the vehicle is in the latter half of the curve, and Correction for reducing the lateral force α may be performed. Further, the marginal lateral force α can be gradually reduced (continuously variable type or stepwise type) in accordance with the elapsed time after entering the curve.

A situation in which the field of view deteriorates is when it is raining, and it is possible to make a correction to increase the marginal lateral force α in this rainy weather. Further, when a deceleration operation by the driver, for example, an operation for fully closing the accelerator opening or a brake operation is detected, the marginal lateral force α can be corrected to a large value. Further, the curvature R of the curve
Is changed (it can be limited to a case where there is a change amount of the curvature R equal to or more than a predetermined value), the marginal lateral force α can be corrected. Various components such as each step or sensor shown in the flowchart can be expressed by adding a name of a means to a higher-level expression of its function. In addition, the object of the present invention is not limited to what is explicitly specified, but also implicitly includes providing what is expressed as substantially preferable or advantageous. Further, the present invention can be expressed as a control method.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining automatic steering for following a target trajectory.

FIG. 2 is a diagram showing an example of a steering system and a control system used for automatic steering.

FIG. 3 is a block diagram showing a control system of FIG. 2;

FIG. 4 is a diagram showing a setting example of a steering torque and a steering torque.

FIG. 5 is a flowchart showing a control example of the present invention.

FIG. 6 is a flowchart showing a control example of the present invention.

FIG. 7 is a flowchart showing a control example of the present invention.

[Explanation of symbols]

 1: vehicle 2: traveling lane 2C: center line (target trajectory yc) 3: front wheel (steering wheel) 4: steering wheel (steering unit) 14: motor (for generating steering torque) 15: motor (for generating steering reaction force) U: controller y1: future lateral deviation amount T1: steering torque (steering reaction force) T2: steering torque (steering force) Ff: target lateral force Ft: actual lateral force α: marginal lateral force

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme court ゛ (Reference) // B62D 101: 00 109: 00 113: 00 125: 00 127: 00 137: 00 F term (Reference) 3D032 CC20 CC21 DA03 DA15 DA23 DA32 DA39 DA46 DA47 DA49 DA82 DA84 DA88 DA91 DA93 DA96 DB13 DB14 DC08 DC09 DC33 DD02 DD05 EA01 EB04 EB11 EB12 EC22 EC29 FF07 GG01 3D041 AA66 AA71 AB01 AD00 AD02 AD04 AD10 AD31 AD41 AD47 AD48 AF00 3G093 AA05 BA04 BA14 CB09 DA01 DA06 DB00 DB01 DB05 DB11 DB15 DB16 DB18 DB24 EA09 EB02 EB03 EC02 FA02 FA03 FA07 FA08 FA10 FB01 FB02 FB04 3G301 JA03 KB06 LA03 LC03 NA06 NC04 ND02 NE01 NE06 PA11A PA11Z PE01Z11 PF01 PF01A01 LL09 LL15

Claims (12)

[Claims] 1. A vehicle control device for controlling automatic steering based on a steering control target value determined to travel along a traveling lane, comprising: a driving force adjusting means for adjusting a driving force of the vehicle; A target lateral force determining means for determining, as a target lateral force, a lateral force required to secure a turn by the control of the automatic steering, based on a driving state of the vehicle related to the turning; Actual lateral force determining means for determining an actually securable lateral force, and the actual lateral force determined by the actual lateral force determining means is greater than a value obtained by adding a marginal lateral force to the target lateral force by a predetermined amount. A driving force control means for controlling the driving force adjustment means so as to reduce the driving force of the vehicle. 2. The vehicle control device according to claim 1, further comprising a correction unit configured to correct the magnitude of the marginal lateral force. 3. The vehicle control device according to claim 2, wherein the correction means is set so as to make the marginal lateral force smaller in a later stage of the turn than in an early stage of the turn. 4. The steering control target value according to claim 2, wherein the steering control target value is determined based on a predicted lateral deviation amount which is a deviation amount in a lateral direction predicted in the future from the currently traveling lane, and Is determined such that when the predicted lateral deviation is large, it is larger than when the predicted lateral deviation is small. 5. The apparatus according to claim 2, wherein the correction means is set to correct the marginal lateral force according to a traveling environment related to a field of view. Vehicle control device. 6. The vehicle control device according to claim 5, wherein the correction means corrects the marginal lateral force to increase during night driving. 7. The control device for a vehicle according to claim 5, wherein the correction means corrects the marginal lateral force so as to increase during traveling on rainy weather. 8. The vehicle according to claim 2, wherein the correcting means corrects the marginal lateral force so that the marginal lateral force is larger when the width of the traveling lane is small than when the width is large.
A control device for a vehicle, comprising: 9. The vehicle control device according to claim 2, wherein the correction means corrects the marginal lateral force to be reduced when the driver requests acceleration. 10. The vehicle control device according to claim 2, wherein the correction means corrects the marginal lateral force so that the marginal lateral force increases when the driver requests a deceleration. 11. The vehicle control device according to claim 2, wherein the correction means corrects the marginal lateral force according to a change in a turning radius. 12. The method according to claim 2, wherein the correction means corrects the marginal lateral force so as to decrease with time.