JP2006027570A - Vehicle behavior estimating method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To promptly, accurately, and easily estimate the roll over possibility of a vehicle. <P>SOLUTION: The vehicle behavior estimating method is a method measuring yaw rate γ and a roll angle ψ generated in a vehicle (ST09), calculating a differential value f' of the roll angle to the yaw rate (ST10), and estimating that the vehicle is in a driving state that may roll over if the differential value exceeds predetermined estimated threshold values LM2. The estimated threshold value has a relative relationship with a yaw angular acceleration dγ calculated from the yaw rate, and decreases in inverse proportion to the yaw angular acceleration (ST11, ST12). Timing for comparing the differential value of the roll angle to the yaw rate and the estimated threshold value is after the roll angle temporarily exceeds a predetermined reference maximum roll angle LM1 (ST02). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a technique for improving a behavior estimation method for estimating the behavior of a vehicle during traveling.

  When the vehicle is turned to the left or right, centrifugal force is applied to the turning vehicle, so that the dampers and springs on the outside of the turn are contracted and the dampers and springs on the inside of the turn are extended among the suspensions that suspend the left and right wheels. As a result, the vehicle body performs a so-called roll motion (rolling; a rotational motion around the longitudinal axis of the vehicle body that passes through the center of gravity) that tilts so that the inside of the turn sinks and the inside of the turn lifts. For this reason, when the vehicle is turning, the vehicle once rolls in the direction opposite to the turning direction, and then reverses in the turning direction and rolls. That is, a rolling phenomenon occurs in the vehicle.

  By the way, while driving a vehicle, for example, entering at a lane junction, interrupting between traveling vehicles, overtaking, avoiding a collision, changing course, etc. (hereinafter collectively referred to as “lane change traveling”) For this reason, there is a case where the steering wheel is rapidly turned back to the other side immediately after once steering to the left or right side. In other words, when performing a lane change travel, the vehicle is once steered to the left or right just before the lane change, and is quickly turned back to the other immediately after the lane change.

  At this time, the direction of the roll motion generated by the next reverse steering matches the direction of the roll motion due to the rebound phenomenon generated by the first steering. When the timing at which the turning-back phenomenon occurs by the initial steering and the timing of the roll motion newly generated by the turning-back steering are combined, the amplitude of the roll at the time of turning back becomes even larger. For this reason, even if the vehicle cannot roll over during normal and proper lane change driving, if the vehicle rolls excessively in lane change driving where the amplitude of the roll is excessive, There is a possibility of rollover due to the reverse phenomenon.

On the other hand, in recent years, development of a vehicle behavior estimation method that estimates the possibility of rollover of a vehicle during traveling of the vehicle, for example, during lane change traveling (for example, see Patent Document 1-2). .)
JP 2003-320830 A JP 2001-50973 A

First, an outline of a conventional vehicle behavior estimation method disclosed in Patent Document 1 will be described with reference to FIG. FIG. 5 is a block diagram for explaining a vehicle rollover prevention device employing a conventional behavior estimation method.
A conventional vehicle rollover prevention device 100 shown in Patent Document 1 includes an operation state detection unit 101, a rollover determination unit 102, a suspension control unit 103, and a suspension rigidity adjustment unit 104. The driving state detection unit 101 includes a vehicle speed detection unit 111, an acceleration detection unit 112, a steering angle detection unit 113, and a steering angular velocity calculation unit 114. The rollover determination unit 102 includes a storage unit 121, a threshold value calculation unit 122, a comparison unit 123, and a determination unit 124.

  According to such a vehicle rollover prevention device 100, the vehicle speed detection unit 111 measures the vehicle speed, the steering angle detection unit 113 and the steering angular velocity calculation unit 114 measure the steering angular velocity, and the threshold calculation unit 122 performs a predetermined operation. A threshold value is set, and the comparison unit 123 compares the vehicle speed and the steering angular velocity with the threshold value. Based on the comparison result, the determination unit 124 can estimate the rollover possibility of the vehicle. The suspension control means 103 that has received the estimation result that there is a possibility of rollover adjusts the damping force characteristic of the shock absorber (damper) by the suspension stiffness adjusting means 104 to strengthen the damper on the current extension side. As a result, the rollover of the vehicle can be prevented.

Next, an outline of a conventional vehicle behavior estimation method disclosed in Patent Document 2 will be described with reference to FIG. FIG. 6 is a block diagram for explaining a vehicle behavior estimation apparatus employing a conventional behavior estimation method.
The conventional vehicle behavior estimation apparatus 200 shown in Patent Document 2 includes wheel speed sensors 203L, 203R, 204L, and 204R that measure the speeds of the left and right front wheels 201L and 201R and the left and right rear wheels 202L and 202R, and the yaw rate generated in the vehicle. A control circuit 206 for generating a control signal based on the signals of the wheel speed sensors 203L, 203R, 204L, 204R and the yaw rate sensor 205, a hydraulic circuit 207 for generating a hydraulic pressure output in response to the control signal, The front hydraulic brake devices 208L and 208R that individually apply a braking force to the left and right front wheels 201L and 201R according to the hydraulic output, and the rear hydraulic brake devices 208L and 208R that individually apply the braking force to the left and right rear wheels 202L and 202R according to the hydraulic output Side hydraulic brake devices 209L and 209R.

According to such a vehicle behavior estimation apparatus 200, the wheel speed sensors 203L, 203R, 204L, 204R measure the speeds of the front wheels 201L, 201R and the rear wheels 202L, 202R, and the yaw rate sensor 205 measures the yaw rate generated in the vehicle. and, the wheels 201L, 201R, 202L, the roll up from calculating the roll angle phi ₀ from the speed and the yaw rate of the 202R, 'calculates the roll angle phi ₀ and the roll rate phi _0' roll rate phi ₀ from the roll angle phi ₀ An estimated value A of the amplitude is calculated, and this estimated value A is used as a fall parameter X indicating the ease of rollover of the vehicle, and the ease of the fall can be estimated by the fall parameter X. Based on this estimation, the hydraulic circuit 207 can apply a braking force to the front wheels 201L or 201R on the outside of the turn by the hydraulic brake devices 208L and 208R, so that the running state of the vehicle tends to be understeered. As a result, the rollover of the vehicle can be prevented.

  However, the conventional vehicle rollover prevention device 100 and the conventional vehicle behavior estimation device 200 do not grasp the behavior such as the roll motion that actually occurs in the vehicle, and thus accurately estimate the possibility that the vehicle rolls over. There is room for improvement.

  An object of the present invention is to provide a technique capable of quickly, accurately, and easily estimating the rollover possibility of a vehicle.

  The invention according to claim 1 is a behavior estimation method for estimating the behavior of a vehicle at the time of traveling, measuring a yaw rate and a roll angle generated in the vehicle, calculating a differential value of the roll angle with respect to the yaw rate, When the value exceeds a preset estimation threshold, it is estimated that the vehicle is in a driving state that may roll over.

  The invention according to claim 2 is characterized in that the estimated threshold value is correlated with the yaw angular acceleration calculated from the yaw rate, and is a value that decreases as the yaw angular acceleration increases.

  The invention according to claim 3 is characterized in that the timing for comparing the differential value of the roll angle with respect to the yaw rate and the estimated threshold value is after the roll angle once exceeds a preset reference maximum roll angle. .

In the invention according to claim 1, by measuring the yaw rate and roll angle generated in the vehicle and calculating the differential value of the roll angle with respect to the yaw rate, the "characteristic of the roll angular velocity with respect to the yaw rate", that is, the yaw rate is changed. The characteristics of the roll angle inclination can be obtained.
When the differential value of the roll angle with respect to the yaw rate exceeds the estimated threshold, the roll angular velocity is excessive with respect to the current yaw rate, and as a result, the vehicle may roll over due to the rolling phenomenon. It can be estimated that there is. In this way, the possibility of rollover of the vehicle can be estimated quickly, accurately and easily.

In the invention according to claim 2, the estimated threshold value is correlated with the yaw angular acceleration calculated from the yaw rate so that the estimated threshold value decreases as the yaw angular acceleration increases.
In general, during steering, after steering the steering wheel to the left or right and then turning back to the other, it is known that the greater the yaw angular acceleration, the greater the roll angular velocity due to the vehicle turning phenomenon. ing. As the roll angular velocity increases, the possibility that the vehicle rolls over increases.

  On the other hand, in claim 2, since the estimation threshold value is reduced as the yaw angular acceleration increases, the estimation timing of the rollover possibility of the vehicle can be advanced as the yaw angular acceleration increases. Accordingly, it is possible to estimate the vehicle rollover possibility more quickly and more accurately. In this way, the rollover possibility of the vehicle can be estimated more quickly and more accurately from the correlation between the yaw angular acceleration and the roll angular velocity.

In the invention according to claim 3, after the measured roll angle once exceeds the preset reference maximum roll angle, the differential value of the roll angle with respect to the yaw rate is compared with the estimated threshold value.
In general, it is known that when a vehicle is suddenly steered to the left or right while traveling, the vehicle greatly rolls in a direction opposite to the steered direction. It can be considered that a large rolling motion can occur in the vehicle after a large roll motion. Rapid detection of such an unstable behavior of the vehicle is indispensable for quickly estimating the possibility of the vehicle rollover.

On the other hand, in claim 3, a reference maximum roll angle is set in advance, and when the measured roll angle is an excessive value that once exceeds the reference maximum roll angle, it is considered that the rolling motion of the vehicle can occur. did. The roll angle once exceeds the reference maximum roll angle and reaches a maximum value, and then descends to be lower than the reference maximum roll angle.
Once the measured roll angle exceeds the reference maximum roll angle, it is quickly detected that an unstable behavior has occurred in the vehicle, which can cause a large rolling motion, and then the roll against the yaw rate is detected. Since the differential value of the angle is compared with the estimated threshold value, the possibility of rollover of the vehicle can be estimated more quickly with good timing.

The best mode for carrying out the present invention will be described below with reference to the accompanying drawings. Note that “front”, “rear”, “left”, “right”, “upper”, and “lower” follow the direction seen from the driver.
FIG. 1 is a schematic plan view of a vehicle behavior control apparatus according to the present invention. The vehicle 10 includes a left and right front wheels 12L and 12R and left and right rear wheels 13L and 13R, a left and right front suspensions 14L and 14R that individually suspend the left and right front wheels 12L and 12R, and left and right rear wheels 13L and 13R. Left and right rear suspensions 15L, 15R, front left and right brake devices 16L, 16R that individually apply braking force to left and right front wheels 12L, 12R, and left and right rear wheels 13L, 13R. The rear left and right brake devices 17L and 17R, the front left and right brake devices 16L and 16R and the rear left and right brake devices 17L and 17R, the steering handle 19, and the vehicle behavior control device 20 It is a four-wheeled vehicle equipped with.

  The vehicle behavior control device 20 is a device that estimates the behavior of the vehicle 10 during traveling and controls the vehicle 10 to prevent rollover according to the estimation result. Such a vehicle behavior control device 20 includes a yaw rate detecting means 21 for measuring the yaw rate γ generated in the vehicle 10, a roll angle detecting means 22 for measuring the roll angle φ generated in the vehicle 10, and the steering angle of the steering handle 19. It comprises a rudder angle detecting means 23 for measuring (including the steering direction), a control unit 24, and a suspension rigidity adjusting means 25.

  Here, the yaw rate γ is a yaw angular velocity when the vehicle body performs a yaw motion (yawing; a rotational motion about a vertical axis passing through the center of gravity with respect to the vehicle body). The roll angle φ is a rotation angle when the vehicle body performs a roll motion (rolling; a rotational motion around the longitudinal axis of the vehicle body passing through the center of gravity).

  The control unit 24 estimates the behavior of the vehicle 10 based on the measurement signals from the yaw rate detection unit 21, the roll angle detection unit 22, and the steering angle detection unit 23, and the brake drive unit 18 and the suspension rigidity according to the estimation result. A control signal is issued to the adjusting means 25, and is composed of, for example, a microcomputer.

  The suspension stiffness adjusting means 25 controls the damping characteristics of the dampers 31L and 31R of the left and right front suspensions 14L and 14R and the dampers 32L and 32R of the left and right rear suspensions 15L and 15R in response to a control signal from the control unit 24. Is.

  By the way, the brake driving means 18 also has a function of individually applying a braking force to the left and right front wheels 12L and 12R by driving the front left and right brake devices 16L and 16R in response to a control signal from the control unit 24.

FIG. 2 is a yaw rate / roll angle characteristic curve diagram according to the present invention, wherein the abscissa represents the yaw rate γ and the ordinate represents the roll angle φ, and the yaw rate γ and the roll angle detecting means measured by the yaw rate detecting means 21 shown in FIG. This is expressed as a γ-φ curve in association with the roll angle φ measured at 22.
The yaw rate γ is a value of ± 0 (zero) at the intersection of the horizontal axis and the vertical axis, the right half of the figure is a positive (+) value and the left half of the figure is a negative (−) value from the intersection. The roll angle φ is a value of ± 0 at the intersection, and the upper half of the figure is a positive (+) ± value and the lower half of the figure is a negative (−) value from the intersection.

According to FIG. 2, it can be seen that when the steering handle in the neutral position is steered to the right, for example, the γ-φ curve changes as follows by turning the vehicle body to the right.
That is, the γ-φ curve (1) extends from ± 0, which is the origin, to the upper right in the figure with a gentle inclination, that is, an upward inclination to the right in the figure, and (2) eventually counterclockwise as the steering angle to the right increases. (3) The yaw rate γ reaches a point Pa where the maximum value γmax is reached when the steering angle is maximized. (4) Thereafter, the roll angle φ increases while the yaw rate γ decreases, so that the roll angle φ increases. To (5) the point Pb at which the roll angle φ reaches the maximum value φmax, and (6) thereafter, a gentle inclination counterclockwise so that both the yaw rate γ and the roll angle φ decrease, that is, the lower left in the figure. (7) After that, the yaw rate γ grows to become a negative value, and (8) eventually the roll angle φ also grows counterclockwise so that the roll angle φ becomes a negative value. .
Here, the reason why the [gamma]-[phi] curve extends with a gentle slope is that the roll motion occurs with a time delay relative to the yaw motion.

Referring to FIG. 2 with reference to FIG. 1, as is clear from the above description, when the vehicle 10 is steered to the right, the vehicle body 11 first rolls in a direction in which the roll angle φ becomes a positive value. (The roll motion is performed so that the right side, which is the inside of the turn, is lifted up), and the roll-back phenomenon occurs after the roll angle φ reaches the maximum φmax, so that the roll motion in the reverse direction, that is, the roll angle φ is negative. Roll in the direction of the value.
Here, the roll motion of the vehicle body 11 in the direction in which the roll angle φ changes from ± 0 to a negative value due to the swinging phenomenon in the case of right steering is referred to as “roll reversal”.

  After the roll angle φ reaches the maximum value φmax, the extent to which the vehicle body 11 rolls in the opposite direction, that is, the magnitude of the amplitude of the rebound roll, is determined from the point Pb, the yaw rate γ and the γ-φ curve. This corresponds to the magnitude of the tilt when tilting downward in the figure so that both roll angles φ decrease. That is, in the γ-φ curve, when the degree of inclination of the tangent Ta that is in contact with the downward curve in the figure is large, the speed at which the vehicle body 11 rolls in the reverse direction, that is, the roll angular speed is also large. If the roll angular velocity at the time of swinging becomes excessive, the amplitude of the roll at the time of swinging also becomes excessive.

Furthermore, if the vehicle is steered once to the right and then quickly turned back to the left immediately thereafter, the next turn-back steering was performed with respect to the direction of the roll motion caused by the turning-back phenomenon generated by the right steering. The direction of the roll motion generated by this is the same. If the timing at which the rollback phenomenon occurs due to the right steering and the timing of the roll motion newly generated by the turnback steering are combined, the roll angular velocity at the time of rollback becomes excessive, so the roll amplitude at the time of rollback Will be even bigger.
Such an excessive rebound phenomenon is not preferable because the possibility that the vehicle 10 rolls over increases.

On the other hand, in the present invention, when the degree of inclination of the tangent Ta exceeds a preset estimated threshold value, “the roll angular velocity at the time of turning is excessive, and as a result, the vehicle 10 can roll over. It is a feature that it is estimated that the vehicle is in a driving state.
The degree of inclination of the tangent Ta that is in contact with the curve at an arbitrary point Pc can be obtained from the differential value f ′ of the roll angle φ with respect to the yaw rate γ.

In the present invention, the reference maximum roll angle LM1 is set in advance, and after the roll angle φ increased by the right steering exceeds the reference maximum roll angle LM1, the estimated value f ′ of the roll angle φ with respect to the yaw rate γ is estimated. It is characterized in that the value LM1 is compared.
More specifically, since the rolling phenomenon of the vehicle body 11 occurs immediately after the roll angle φ reaches the maximum value φmax, the differential value is taken into consideration when the roll angle φ starts to decrease from the maximum φmax. f ′ and the estimated threshold value LM1 are compared. That is, in the γ-φ curve, the threshold value P ′ is estimated at the point Pd at which the roll angle φ reaches the maximum value φmax and thereafter both the yaw rate γ and the roll angle φ start to decrease. Compared with the value.

  As a matter of course, when the steering handle 19 in the neutral position is steered to the left, the vehicle body 11 steers to the left, so that the γ-φ curve extends in the opposite direction to the right steering described above. .

  Next, a control flow when the control unit 24 having the above configuration is a microcomputer will be described based on FIG. 3 with reference to FIGS. 1 and 2. In the figure, STxx indicates a step number. Step numbers that are not specifically described proceed in numerical order.

FIG. 3 is a control flowchart of the control unit according to the present invention.
ST01: The latest roll angle φ is measured. The roll angle φ may be measured by the roll angle detection means 22 of FIG.
ST02: It is checked whether or not the roll angle φ exceeds a predetermined reference maximum roll angle LM1 (φ> LM1). If NO, the process proceeds to ST03, and if YES, the process proceeds to ST06. In the case of YES, it is determined that the roll-back phenomenon of the vehicle 10 may occur because the roll angle φ is excessive.

ST03: Since the roll angle φ is still small, the latest roll angle φ is measured again. The roll angle φ may be measured by the roll angle detection means 22 of FIG.
ST04: The roll angular velocity dφ is obtained by differentiating the roll angle φ.

  ST05: Check whether the value obtained by multiplying the roll angular velocity dφ by the roll angle φ is less than 0 (zero), that is, a negative value, that is, whether the condition “(dφ × φ) <0” has been achieved. If NO, the process returns to ST01. If YES, it is determined that the roll angle φ has started to drop, and the control is terminated. Note that when the roll angle φ starts to decrease, the yaw rate γ starts to decrease first.

In the case of YES in this step ST05, it is determined that the roll angle φ has started to drop before exceeding the reference maximum roll angle LM1, and there is no occurrence of the rolling-back phenomenon of the vehicle 10.
In addition to the first steering pattern in which the vehicle 10 is steered to the right after first turning to the left, the second steering pattern in which steering is steered to the right after first turning to the left is included in the steering pattern of the vehicle 10. There is. In step ST05, whether or not “dφ × φ” is a negative value can be determined in any of the first and second steering patterns in order to determine whether or not the roll angle φ has started to decrease. I asked for it. This is because in the second steering pattern, the roll angle φ is initially a negative value and then turns to a positive value.

ST06: Since the roll angle φ is excessive, the latest roll angle φ is measured again. The roll angle φ may be measured by the roll angle detection means 22 of FIG.
ST07: The roll angle φ is differentiated to obtain the roll angular velocity dφ (roll angle differential value dφ).

  ST08: Check whether the value obtained by multiplying the roll angular velocity dφ and the roll angle φ is less than 0 (zero) and negative, that is, whether the condition “(dφ × φ) <0” is achieved. If NO, the process returns to ST06. If YES, the roll angle φ is determined to have started to decrease from the maximum φmax, and the process proceeds to ST09. Note that when the roll angle φ starts to decrease, the yaw rate γ starts to decrease first. In the case of YES, the estimation about the possibility of the vehicle 10 rollover is started.

  As described in step ST05 above, the steering pattern of the vehicle 10 includes the first steering pattern in which the vehicle turns to the left after first turning to the right, and then turns to the right after first turning to the left. There is a second steering pattern in which the steering is turned back. In step ST08, whether or not “dφ × φ” is a negative value is determined in order to be able to determine whether the roll angle φ has started to decrease in either of the first and second steering patterns. I made it. This is because in the second steering pattern, the roll angle φ is initially a negative value and then turns to a positive value.

  ST09: The latest yaw rate γ and roll angle φ are measured. For the yaw rate γ, the actual yaw rate γ may be measured by the yaw rate detecting means 21 of FIG. The roll angle φ may be measured by the roll angle detection means 22 of FIG.

  ST10: A differential value f ′ of the roll angle φ with respect to the yaw rate γ at the present time is obtained from the measured value obtained in step ST09. The differential value f ′ is the degree of inclination of the tangent line Ta in contact with the curve at the current point Pc among the curves descending to the left in the γ-φ curve shown in FIG.

ST11: The yaw rate γ obtained in ST09 is differentiated to obtain the yaw angular acceleration dγ (yaw rate differential value dγ).
ST12: The estimated threshold value LM2 is obtained from the yaw angular acceleration dγ using the estimated threshold value characteristic map shown in FIG. A characteristic map of the estimated threshold value is as shown in FIG.

  FIG. 4 is a characteristic map of estimated threshold values according to the present invention. This map has an estimated threshold value LM2 corresponding to the yaw angular acceleration dγ, with the horizontal axis indicating the yaw angular acceleration dγ and the vertical axis indicating the estimated threshold value LM2. It is the estimated threshold value characteristic curve figure which obtains.

  According to this estimated threshold value characteristic map, the estimated threshold value LM2 is correlated with the yaw angular acceleration dγ calculated from the yaw rate γ, and is a value that decreases as the yaw angular acceleration dγ increases. I understand that. That is, the estimated threshold value characteristic map indicates that the estimated threshold value LM2 tends to be approximately inversely proportional to the yaw angular acceleration dγ.

More specifically, the characteristic of the estimated threshold value LM2 is the maximum when the yaw angular acceleration dγ is close to 0, decreases rapidly as the yaw angular acceleration dγ increases, and the yaw angular acceleration dγ exceeds a certain value. The characteristic has an almost constant minimum value.
With such an estimated threshold characteristic map, the estimated threshold LM2 corresponding to the yaw angular acceleration dγ at that time can be obtained.

Returning to FIG. 3, the continuation of the control flow will be described.
ST13: It is checked whether or not the differential value f ′ exceeds the estimated threshold value LM2 (f ′> LM2). If NO, it is determined that there is no possibility of rollover of the vehicle 10, and the process proceeds to ST14. It judges that it is driving | operation with possibility of rollover, and progresses to ST15.

  ST14: Although the rolling phenomenon of the vehicle 10 has occurred, it is determined that there is no possibility of the vehicle 10 rolling over, so the damping characteristics of the dampers 31L, 31R of the front suspensions 14L, 14R are controlled via the suspension stiffness adjusting means 25. After that, this control is finished.

In this step ST14, for example, when a rolling phenomenon occurs in the vehicle 10, while the vehicle 10 is rolling in the reverse direction to the neutral position, the damper 31L or 31R on the current extension side is strengthened. The damping characteristics of the dampers 31L and 31R are controlled. Thereafter, the damping characteristics of the dampers 31L and 31R are controlled so that the damper 31L or 31R on the current contraction side is strengthened while the vehicle 10 is rolling in the opposite direction from the neutral position, that is, when the roll is reversed. As a result, the roll motion of the vehicle 10 when the rolling phenomenon occurs can be suppressed, and more stable lane change traveling can be performed.
can do.

As such a damper damping characteristic control method, for example, an electrical damping characteristic changing means (not shown) is built in the dampers 31L and 31R, and a drive current for driving the damping characteristic changing means is set as follows. This is executed by changing the roll angular velocity dφ of the vehicle 10.
There are various damper damping characteristic control methods in step ST14, and the method is not limited to the above-described control method.

  ST15: Since it has been determined that the operation has the possibility of rollover due to the occurrence of the rolling back phenomenon, the front and right brake devices 16L and 16R are controlled via the brake drive means 18, and then this control is terminated. Specifically, a turning force of the vehicle 10 is suppressed by applying a braking force to one of the left and right front wheels 12L and 12R that becomes a turning outer wheel to slip the turning outer wheel (restricting rotation).

  In step ST15, the turning motion of the vehicle 10 can be suppressed by slipping the turning outer wheel 12L or 12R even if the steering is rapidly turned back to the other immediately after the lane change. Therefore, since it is possible to suppress the yaw rate γ from changing greatly during the turn-back steering, the roll angle φ and the roll angular velocity dφ of the vehicle 10 can be suppressed and the rollover of the vehicle 10 can be prevented.

Thus, depending on whether or not the vehicle 10 is likely to roll over in step ST13, that is, depending on the degree of rolling of the vehicle 10, (1) suspension control in step ST14, and (2) step The brake control in ST15 is selected. For this reason, only when it is determined that the vehicle has a possibility of rollover due to the occurrence of the swing-back phenomenon, the turning outer wheel by the brake control can be slip-controlled.
Since the slip control is different from the general steering feeling of the driver, the driver feels uncomfortable. Such a slip with a sense of incongruity can be suppressed as much as possible.

The vehicle behavior estimation method described above is summarized as follows.
In the present invention, as shown in FIGS. 1 to 3, the yaw rate γ and the roll angle φ generated in the vehicle 10 are measured, and the differential value f ′ of the roll angle φ with respect to the yaw rate γ is calculated, thereby changing every moment. “Characteristics of roll angular velocity dφ with respect to yaw rate γ”, that is, characteristics of the inclination of roll angle φ with respect to yaw rate γ can be obtained.
When the differential value f ′ of the roll angle φ with respect to the yaw rate γ exceeds the estimated threshold value LM2, the roll angular velocity dφ is excessive with respect to the current yaw rate γ, and as a result, the vehicle 10 rolls over due to the rolling phenomenon. It can be estimated that the operation state is likely to occur. In this way, the possibility of rollover of the vehicle 10 can be estimated quickly, accurately and easily.

  By the way, in general, after the steering handle 19 is steered to the left or right and then turned back to the other during traveling, the roll angular velocity dφ due to the rolling phenomenon of the vehicle 10 increases as the yaw angular acceleration dγ increases. It is known to be. As the roll angular velocity dφ increases, the possibility that the vehicle 10 rolls over increases.

On the other hand, in the present invention, as shown in FIG. 4, the estimated threshold value LM2 is decreased as the yaw angular acceleration dγ is increased. Therefore, as the yaw angular acceleration dγ is increased, the rollover possibility of the vehicle 10 is increased. The estimation timing can be advanced. Therefore, the rollover possibility of the vehicle 10 can be estimated more quickly and more accurately.
In this way, the rollover possibility of the vehicle 10 can be estimated more quickly and more accurately from the correlation between the yaw angular acceleration dγ and the roll angular velocity dφ.

  In general, it is known that when the vehicle 10 is suddenly steered to the left or right while traveling, the vehicle 10 largely rolls in a direction opposite to the steered direction. It can be considered that a large rolling motion can occur in the vehicle 10 after a large roll motion. Rapid detection of such an unstable behavior of the vehicle 10 is indispensable for quickly estimating the rollover possibility of the vehicle 10.

On the other hand, in the present invention, as shown in FIGS. 2 and 3, when the reference maximum roll angle LM1 is set in advance and the measured roll angle φ is an excessive value that once exceeds the reference maximum roll angle LM1, It was decided that 10 swinging motions could occur. The roll angle φ once exceeds the reference maximum roll angle LM1 and reaches the maximum value φmax, and then falls to be lower than the reference maximum roll angle LM1.
When the measured roll angle φ once exceeds the reference maximum roll angle LM1, it is quickly detected that an unstable behavior has occurred in the vehicle 10 such that a large rolling motion may occur. Since the differential value f ′ of the roll angle φ with respect to the yaw rate γ is compared with the estimated threshold value LM2, the rollover possibility of the vehicle 10 can be estimated more quickly with good timing.

  The vehicle behavior estimation method of the present invention and the vehicle behavior control device 20 employing this method are suitable for vehicles such as passenger cars.

1 is a schematic plan view of a vehicle behavior control device according to the present invention. It is a yaw rate roll angle characteristic curve figure concerning the present invention. It is a control flowchart of the control part which concerns on this invention. It is a characteristic map of the estimated threshold value which concerns on this invention. It is a block diagram explaining the vehicle rollover prevention apparatus which employ | adopted the conventional behavior estimation method. FIG. 6 is a block diagram for explaining a vehicle behavior estimation apparatus employing a conventional behavior estimation method.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Vehicle, 11 ... Vehicle body, 12L, 12R ... Left and right front wheels, 13L, 13R ... Left and right rear wheels, 14L, 14R ... Left and right front suspensions, 15L, 15R ... Left and right rear suspensions, 16L, 16R ... Front left and right Brake device, 17L, 17R ... rear left and right brake devices, 18 ... brake drive means, 19 ... steering handle, 20 ... vehicle behavior control device, 21 ... yaw rate detection means, 22 ... roll angle detection means, 23 ... control unit, 24: Suspension stiffness adjusting means, 31L, 31R: Left and right front suspension dampers, 32L, 32R: Left and right rear suspension dampers, f ': Differential value of roll angle with respect to yaw rate, LM1: Reference maximum roll angle, LM2: Estimated Threshold value, γ ... yaw rate, dγ ... yaw angular acceleration, φ ... roll angle.

Claims (3)

  A behavior estimation method for estimating the behavior of a vehicle at the time of traveling, measuring a yaw rate and a roll angle generated in the vehicle, calculating a differential value of the roll angle with respect to the yaw rate, and estimating the differential value in advance. A vehicle behavior estimation method, characterized in that when the threshold value is exceeded, it is estimated that the vehicle is in a driving state that may roll over.   2. The vehicle behavior estimation according to claim 1, wherein the estimated threshold value is correlated with a yaw angular acceleration calculated from the yaw rate, and is a value that decreases as the yaw angular acceleration increases. Method. The timing at which the differential value of the roll angle with respect to the yaw rate is compared with the estimated threshold value is after the roll angle has once exceeded a preset reference maximum roll angle. Item 3. A vehicle behavior estimation method according to Item 2.

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