JPH095352A - Vehicle lateral acceleration detection device - Google Patents

Abstract

(57) [Abstract] [Object] The present invention relates to a lateral acceleration detection device for a vehicle, and an object thereof is to prevent deterioration of accuracy of a lateral acceleration detection value. A lateral acceleration detection device for a vehicle obtains a lateral acceleration applied to the vehicle using a lateral acceleration sensor M1 attached to the vehicle. The roll angle estimating means M2 estimates the roll angle of the vehicle based on the lateral acceleration detected by the lateral acceleration sensor M1. The roll angle correction means M3 corrects the lateral acceleration detected by the lateral acceleration sensor based on the estimated roll angle.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle lateral acceleration detecting device, and more particularly to a device for detecting lateral acceleration applied to a vehicle.

[0002]

2. Description of the Related Art Conventionally, a sensor detects a lateral acceleration applied to a vehicle at the time of turning, and a driving force of an engine or a braking force of each wheel is controlled according to the detected lateral acceleration to control a turning behavior of the vehicle. Stabilization is taking place.

For example, in Japanese Patent Laid-Open No. 2-70937, the driving force of an engine is reduced according to the detection output of a lateral acceleration sensor to prevent wheel slippage during turning.
In addition, when the lateral acceleration sensor fails, the centripetal acceleration is obtained from the wheel speed of each of the left and right driven wheels, and the acceleration slip prevention device is described that reduces the driving force of the engine according to the centripetal acceleration to prevent the occurrence of slip during turning. ing.

[0004]

In the conventional acceleration slip prevention device, the centripetal acceleration is obtained when the lateral acceleration sensor fails, but even if the lateral acceleration sensor does not fail, the lateral acceleration sensor can be used. In some cases, the accuracy of acceleration detection deteriorates, and appropriate control cannot be performed.

The acceleration output value of the lateral acceleration sensor and the error amount have the relationship shown in FIG. 9, and even when the acceleration output value is 0, the error amount is in the range of -0.1 g to 0.1 g. This error is caused by a drift of the neutral point due to an installation error of the lateral acceleration sensor, a load balance of the vehicle being unbalanced, or the like. Also, when the vehicle rolls, the acceleration output value of the lateral acceleration sensor fluctuates due to the influence of gravitational acceleration.

There is a problem that the lateral acceleration detected by the lateral acceleration sensor has an error due to the neutral point drift and the vehicle roll angle, and the detection accuracy is deteriorated. The present invention has been made in view of the above points, by estimating the roll angle of the vehicle based on the lateral acceleration sensor output, and by correcting the lateral acceleration detected by the lateral acceleration sensor based on the estimated roll angle, An object of the present invention is to provide a lateral acceleration detecting device for a vehicle, which prevents a decrease in the accuracy of the detected acceleration value.

Further, according to the present invention, the neutral point drift amount is obtained from the deviation between the lateral acceleration estimated from the wheel speeds of the left and right wheels and the lateral acceleration sensor output, and the lateral acceleration detected by the lateral acceleration sensor is calculated from this neutral point drift amount. An object of the present invention is to provide a lateral acceleration detecting device for a vehicle, which is capable of preventing the accuracy of the lateral acceleration detection value from being lowered by the correction.

[0008]

According to a first aspect of the present invention, as shown in FIG. 1A, a lateral acceleration of a vehicle for determining a lateral acceleration applied to the vehicle using a lateral acceleration sensor M1 attached to the vehicle. In the detection device, the roll angle estimating means M2 for estimating the roll angle of the vehicle based on the lateral acceleration detected by the lateral acceleration sensor M1, and the lateral acceleration detected by the lateral acceleration sensor based on the estimated roll angle are corrected. And a roll angle correcting means M3.

According to a second aspect of the present invention, as shown in FIG. 1B, in a lateral acceleration detecting device for a vehicle, the lateral acceleration applied to the vehicle is obtained from a detection output of a lateral acceleration sensor M1 attached to the vehicle. Lateral acceleration estimating means M4 for estimating lateral acceleration from the wheel speeds of the left and right wheels, an average value of lateral accelerations detected by the lateral acceleration sensor in a predetermined period, and an average value of lateral accelerations estimated by the lateral acceleration estimating means. Of the neutral point drift amount, and a neutral point drift correction unit M6 that corrects the lateral acceleration detected by the lateral acceleration sensor based on the neutral point drift amount.

[0010]

In the invention described in claim 1, the roll angle of the vehicle is estimated from the lateral acceleration detected by the lateral acceleration sensor,
The gravitational acceleration component that is superimposed on the lateral acceleration detected by the lateral acceleration sensor is calculated from this estimated roll angle to correct the lateral acceleration detected by the lateral acceleration sensor. It is possible to prevent the accuracy of lateral acceleration from being lowered.

According to the second aspect of the present invention, the deviation between the lateral acceleration estimated from the wheel speeds of the left and right wheels and the lateral acceleration detected by the lateral acceleration sensor is obtained as the neutral point drift amount, and the lateral point drift amount is used to determine the lateral point. Since the lateral acceleration detected by the acceleration sensor is corrected, it is possible to prevent the accuracy of the lateral acceleration obtained by correcting the error caused by the lateral acceleration sensor installation error or the deviation of the vehicle load distribution, etc. By obtaining the deviation between the average value of the lateral accelerations and the average value of the detected lateral accelerations as the neutral point drift amount, it is possible to obtain a highly accurate neutral point drift amount that is less affected by the calculation timing and noise.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 2 is a schematic block diagram of an embodiment of the device of the present invention. In the figure, left and right front wheels 11, 12 and left and right rear wheels 13,
Wheel speed sensors 21, 22, 23, 24 are provided in each of the fourteen wheel wheels, and the wheel speed detection signals of the four wheels detected by the wheel speed sensors 21-24 (M1) are electronic control circuits (ECU). 25.

A lateral acceleration sensor 3 fixed to the vehicle body
2 detects the lateral acceleration of the vehicle, and the detection signal of this lateral acceleration is supplied to the ECU 25. As shown in FIG. 3, the ECU 25 includes a central processing unit (CPU) 40, a read-only memory (ROM) 42 storing processing programs, and a random access memory (RA) used as a work area.
M) 44 and an input port circuit 4 including an A / D converter
6, an output port circuit 48, and an electric erasable programmable read only memory (EEPROM) 50 which is a non-volatile memory, which are connected to each other by a bidirectional bus 52. A signal detected by each of the wheel speed sensors 21 to 24 and a signal detected by each of the lateral acceleration sensors 32 are input to the input port circuit 46.

FIG. 4 shows a flow chart of an embodiment of the lateral acceleration correction processing executed by the CPU 40. In the figure, in step S10, the detected lateral acceleration Gy1 detected by the lateral acceleration sensor 32 is read, and the left front wheel FL, the right front wheel FR, the left rear wheel RL, and the right rear wheel RR detected by the wheel speed sensors 21 to 24 are read.
The respective wheel speeds Vfl, Vfr, Vrl, Vrr are read.

Next, in step S12 corresponding to the roll angle estimating means M2 and the roll angle correcting means M3, the error of the lateral acceleration sensor output due to the roll of the vehicle is corrected. By the way, as shown in FIG. 5, when the vehicle body 60 is laterally inclined by the roll angle θ, Gy = Gy ^* · Cosθ + g · sin between the measured lateral acceleration value Gy and the actual lateral acceleration Gy ^*.
There is a θ relationship. From this, Gy ^* = (Gy−g · sin θ) / cos θ (1) where g is the gravitational acceleration and the roll angle θ of the vehicle is expressed by the roll rigidity γ of the vehicle as shown in FIG. .

Θ = γ (Gy ^* ) · Gy ^* (2) In this equation (2), the measured lateral acceleration Gy is used instead of the actual lateral acceleration Gy ^* to obtain the approximate roll angle θ ′. θ ′ = γ (Gy) · Gy (3) This equation (3) is substituted into the equation (1) to obtain the lateral acceleration Gy ′ in which the error due to the vehicle roll is corrected.

Gy ′ = (Gy−g · sin θ ′) / cos θ ′ (4) In step S12, the roll angle θ is calculated by using the detected lateral acceleration Gy1 as the measured lateral acceleration Gy in the equations (3) and (4). 'And roll angle correction lateral acceleration Gy1' are obtained. θ ′ = γ (Gy1) · Gy1 Gy1 ′ = (Gy1-g · sin θ ′) / cos θ ′ Next, in step S14, the lateral acceleration Gy2 is estimated from the wheel speeds Vfl and Vfr of the front wheels, and the wheel speed of the rear wheels is also calculated. Vrl, V
The lateral acceleration Gy3 is estimated from rr.

[0018] ^{Gy2 = (Vfl 2 -Vfr 2)} / 2 · df ... (5) Gy3 = (Vrl 2 -Vrr 2) / 2 · dr ... (6) However, df is the front tread, dr is the rear tread . After that, the routine proceeds to step S16, and steady running determination is performed. Here, the vehicle body acceleration d obtained by differentiating the vehicle body speed V _S0 calculated by the ABS (anti-lock brake system)
Whether the acceleration or deceleration is not performed when the absolute value of V _S0 is less than a constant K ₀ , and the estimated lateral acceleration difference between the front and rear wheels Gy2-Gy3
Is less than a constant k ₁ and the vehicle is not spinning, the roll angle correction lateral acceleration Gy1 ′ is less than a constant k ₂ , the estimated lateral acceleration Gy2 is less than a constant k ₃ , and the estimated lateral acceleration Gy3 is
Is less than a constant k ₄ and is in a low lateral acceleration state, and whether the wheel speeds Vfl, Vfr, Vrl, Vrr are all above 0 and the vehicle is traveling.

When it is determined that the vehicle is accelerating or decelerating, the vehicle is spinning, the vehicle is laterally accelerated, or the vehicle is stopped, step S1 is performed.
The process proceeds to 0 and the processes of steps S10 to S14 are repeated. If the vehicle is not accelerating or decelerating, the vehicle is not spinning, and the vehicle is traveling at a low lateral acceleration, the process proceeds to step S18 to obtain the neutral point drift amount. This is because the neutral point drift amount cannot be accurately obtained during large acceleration / deceleration or when the lateral acceleration is large, and lateral acceleration does not occur when the vehicle is stopped. This is because the drift amount may change.

In step S18, the standard time T shown in FIG.
In, the addition averages Gy1A and Gy2A of the roll angle correction lateral acceleration Gy1 ′ and the estimated lateral acceleration Gy2 obtained at each sampling cycle t ^* are obtained, and the neutral point drift amount α is obtained from them.

[0021]

[Equation 1]

Thereafter, in step S20, it is determined whether or not α obtained by the equation (7) is within the range of −k ₅ to k ₅ represented by the constant k ₅ . Here, if −k ₅ ≧ α or α ≧ k ₅ , that is, if the neutral point drift amount α is too large, the reliability is low, so that value is discarded in step S.
The process proceeds to step 10, and steps S10 to S20 are repeated. If -k ₅ <α <k ₅ , the process proceeds to step S22 and the neutral point drift amount α is held. Step S above
14 and S18 correspond to the neutral point drift amount calculation means M5.

Next, in step S24, abnormality detection, which will be described later, is performed.
After executing the processing, the process proceeds to step S26, where the same value
The neutral point drift amount α can be obtained a predetermined number of times m (for example, m is several times).
Is determined. If it does not reach m times, step
The process proceeds to step S10 and steps S10 to S26 are repeated.
When α of the same value is obtained m times, the process proceeds to step S26,
Α of α_nHold as_nAnd the neutrality of the past
Point correction value α^* _n-1~ Α ^* _nxAnd neutralize a new neutral
Point correction value α^*Ask for.

Α ^* = (α _n + α ^* _n-1 + ... + α ^* _nx ) / (x + 1) (8) By using the above equation (8), the neutral point correction value α ^*
Are averaged, and the neutral point correction value α ^* _{n in} a state where the load is biased to the right side of the vehicle does not project, for example.

Next, at step S30, the neutral point correction value α^*But
Constant k₆Represented by -k₆To k ₆Within the range up to
Whether it is -k₆<Α^*<K₆In case of, step S3
2 in α^*Is a new neutral point correction value α^* _nSet to
Go to step S34. -K in step S30₆≧ α^*Or
α^*≧ k₆In the case of, go to step S36 and -k₆≧ α
^*Whether or not it is determined. And -k₆≧ α^*If so
New neutral point correction value α in step S38^* _nTo -k₆The
Then, the process proceeds to step S34. Also, -k₆<Α^*In
Then, in step S40, a new neutral point correction value α^* _nTo k₆
Is set and the process proceeds to step S34.

That is, the new neutral point correction value α ^* _n is -k
_A guard is provided so as not to fall below ₆ or exceed k ₆ , to prevent the new neutral point correction value α ^* _n from exceeding the originally intended range, and prevent erroneous correction. In step S34 corresponding to the neutral point drift amount correcting means M6, the roll angle correction lateral acceleration Gy1 ′ is corrected using the new neutral point correction value α ^* _n obtained as described above, and the corrected lateral acceleration Gy1 is corrected. Then, the process proceeds to step S10 and this process is repeated.

Thus, the deviation between the lateral acceleration Gy2A estimated from the wheel speeds of the left and right wheels and the lateral acceleration Gy1A detected by the lateral acceleration sensor is obtained as the neutral point drift amount α,
Since the lateral acceleration Gy1 ″ detected by the lateral acceleration sensor is corrected based on the neutral point drift amount, the accuracy of the lateral acceleration obtained by correcting an error due to a mounting error of the lateral acceleration sensor, a deviation of load distribution of the vehicle, or the like is reduced. Further, by obtaining the deviation between the average value of the estimated lateral acceleration and the average value of the detected lateral acceleration in the predetermined period T as the neutral point drift amount α ^* , it is difficult to be affected by the calculation timing and noise, and the high-precision neutral point is obtained. The amount of drift can be calculated.

In this embodiment, the rear-wheel drive is premised, and the neutral point drift amount α is obtained using the lateral acceleration Gy2 estimated based on the wheel speed of the front wheels to which no driving force is applied. As a result, it is possible to prevent the wheel speed from changing due to the driving force and the accuracy of the lateral acceleration estimated from the wheel speed from decreasing. Therefore, in the case of front-wheel drive,
The lateral acceleration Gy3 estimated from the wheel speed of the rear wheels may be used.

FIG. 8 shows a detailed flow chart of the abnormality detection processing (step S24). In the figure, step S50
Then, the neutral point drift amount α is represented by a predetermined value k ₇ −k
It is determined whether or not it is within the range of ₇ to k ₇ . Here -k ₇ <alpha ended zero reset processing the <k ₇ a long If the counter in step S52 N.

In step S50, -k ₇ ≥α or α
If ≧ k ₇ , the neutral point drift amount α is too small or too large and there is a possibility of an abnormality, so the counter N is incremented by 1 in step S54. Next, step S5
In step 6, it is determined whether or not the value of the counter N exceeds a predetermined value y (y is a value larger than m), and if N ≧ y, the process ends. When N <y, the lateral acceleration sensor 3
It is regarded as the second abnormality, and the abnormality is detected in step S58, and the process ends.

Here, if the number of times the neutral point drift amount α exceeds the range given by the constant k ₇ and becomes too small or too large continues for a predetermined number of times y, for example, the sensor 32 is damaged,
It is considered that an abnormality has occurred due to deformation of the attachment of the sensor 32, damage to the shock absorber, or the like. Of course, an alarm may be issued in step S58.

[0032]

As described above, according to the first aspect of the present invention, the roll angle of the vehicle is estimated from the lateral acceleration detected by the lateral acceleration sensor, and this estimated roll angle is used as the lateral acceleration detected by the lateral acceleration sensor. Since the superimposed gravitational acceleration component is obtained to correct the lateral acceleration detected by the lateral acceleration sensor, it is possible to prevent the accuracy of the lateral acceleration obtained by removing the error in the detected value of the lateral acceleration due to the vehicle roll from being lowered.

According to the second aspect of the present invention, the deviation between the lateral acceleration estimated from the wheel speeds of the left and right wheels and the lateral acceleration detected by the lateral acceleration sensor is obtained as the neutral point drift amount, and the neutral point drift amount is used. Since the lateral acceleration detected by the lateral acceleration sensor is corrected, it is possible to prevent the accuracy of the lateral acceleration obtained by correcting the error due to the mounting error of the lateral acceleration sensor or the deviation of the load distribution of the vehicle, etc. By obtaining the deviation between the average value of the estimated lateral acceleration and the average value of the detected lateral acceleration as the neutral point drift amount, it is possible to obtain a highly accurate neutral point drift amount that is not easily affected by the calculation timing and noise. It is useful.

[Brief description of drawings]

FIG. 1 is a principle diagram of the present invention.

FIG. 2 is a schematic block diagram of the device of the present invention.

FIG. 3 is a block diagram of an ECU.

FIG. 4 is a flowchart of lateral acceleration correction processing.

FIG. 5 is a diagram for explaining a vehicle roll.

FIG. 6 is a diagram showing a relationship between lateral acceleration and roll rigidity.

FIG. 7 is a diagram for explaining calculation of a neutral point drift amount.

FIG. 8 is a flowchart of abnormality detection processing.

FIG. 9 is a diagram showing a relationship between an acceleration output value of a lateral acceleration sensor and an error amount.

[Explanation of symbols]

 11-14 Wheels 21-24 Wheel speed sensor 25 ECU 32, M1 Lateral acceleration sensor 40 CPU 42 ROM 44 RAM 46 Input port circuit 48 Output port circuit 50 EEPROM 52 Bus M2 Roll angle estimating means M3 Roll angle correcting means M4 Lateral acceleration estimating Means M5 Neutral point drift amount calculation means M6 Neutral point drift amount correction means

Claims (2)

[Claims] 1. A lateral acceleration detecting device for a vehicle, which uses a lateral acceleration sensor mounted on a vehicle to determine a lateral acceleration applied to the vehicle, wherein a roll angle of the vehicle is estimated based on the lateral acceleration detected by the lateral acceleration sensor. A lateral acceleration detecting device for a vehicle, comprising: a roll angle estimating means; and a roll angle correcting means for correcting a lateral acceleration detected by the lateral acceleration sensor based on the estimated roll angle. 2. A lateral acceleration detecting device for determining a lateral acceleration applied to the vehicle from a detection output of a lateral acceleration sensor attached to the vehicle, wherein the lateral acceleration estimating means estimates lateral acceleration from wheel speeds of left and right wheels of the vehicle. A neutral point drift amount calculation means for obtaining a deviation between an average value of lateral acceleration detected by the lateral acceleration sensor in a predetermined period and an average value of lateral acceleration estimated by the lateral acceleration estimation means as a neutral point drift amount; A lateral acceleration detection device for a vehicle, comprising: a neutral point drift correction unit that corrects the lateral acceleration detected by the lateral acceleration sensor based on the amount of neutral point drift.