JPH087225B2 - Vehicle running condition calculator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a vehicle traveling state (turning) used as control input information in differential limiting amount control of a differential device, front / rear wheel driving force distribution control of a transfer device, and the like. Radius, vehicle speed, yaw rate,
The present invention relates to a vehicle traveling state calculation device that calculates centripetal acceleration and the like.

(Prior Art) Conventionally, as a sensor for obtaining centripetal acceleration, which is one of the running states of a vehicle, as input information, for example, a device using a well-known acceleration sensor using magnetic fluid, or Japanese Patent Publication No. 59-19
The device described in Japanese Patent Publication No. 94 is known.

The former conventional device is a device that encloses a magnetic fluid, detects the deformation of the magnetic fluid according to the acceleration acting in the centripetal direction by the difference in the inductance of the two coils, and directly obtains the centripetal acceleration by the output voltage. In addition, the latter conventional device,
The vehicle speed and the steering angle at the time of steering the steering wheel are detected, the detected values are used as input signals, and an output signal which is approximately proportional to the product of the square of the vehicle speed and the tangent of the steering angle is obtained by a function generator. Is a device for obtaining the centrifugal force (centripetal acceleration x vehicle weight) generated when the vehicle turns.

(Problems to be Solved by the Invention) However, in the former conventional device, the price is high, and the gravitational acceleration component is also detected by the vehicle body inclination due to the rolling roll, and the vehicle body roll is detected and output. There is a problem in that accurate centripetal acceleration cannot be obtained without correcting the signal.

Further, in the latter conventional device, when it is difficult to detect the absolute neutral position of the steering angle and a slip angle is attached during high-speed turning, the road surface friction coefficient is not detected and the calculated value is not corrected. However, there is a problem in that an accurate centrifugal force (centripetal acceleration) cannot be obtained.

On the other hand, the applicant of the present application has proposed a prior art having a content for solving the above-mentioned problems in the application of Japanese Patent Application No. 61-292016 (Japanese Patent Publication No. 06-0777023).

However, in this prior art, correction is performed when the difference between the left and right wheel rotational accelerations exceeds a set value, and this correction is performed by changing the corrected wheel rotational speed on the side with a large rotational acceleration to the corrected rotational speed one cycle before. Since it is a device that obtains by adding the increase in the rotational acceleration on the smaller side, the difference between the rotational accelerations of the left and right wheels exceeds the set value and is calculated by the corrected wheel rotational speed. If the speed returns within the set value, the difference between the actual left / right wheel speed difference and the corrected left / right wheel speed difference for calculation just before the return will be large, and the result calculated at the moment of return will change significantly. Especially, when the vehicle runs straight on the split μ road, there remains a problem that the correction is completed before the wheel rotational speed difference becomes normal.

(Means for Solving the Problems) The present invention has been made for the purpose of solving the problems described above, and in order to achieve this object, the present invention has the following solution means.

The solution means of the present invention will be described with reference to the claim correspondence diagram shown in FIG. 1. Left wheel rotation speed detection means a and right wheel rotation speed detection means b for detecting left and right wheel rotation speeds W ₁ and W ₂ , respectively, and Left wheel rotational acceleration calculation means c and right wheel rotational acceleration calculation means for calculating rotational accelerations ₁ and ₂ of the left and right wheels respectively by detecting increase / decrease of the left wheel rotational speed W ₁ and the right wheel rotational speed W ₂ by the detection means a and b. d and the calculation means c, d
Of the rotational accelerations ₁ and ₂ of the left and right wheels obtained by the above, the first correction means e that corrects the wheel rotational speed on the side of large rotational acceleration based on the rotational speed on the side of small rotational acceleration.
A second correction means f for gradually matching the actual wheel rotation speeds W ₁ , W ₂ after the correction by the first correction means e, and the first and second correction means e , f, the left wheel rotation speed W ₁ obtained by including the corrected rotation speed
^{* And a} right-wheel rotation speed W ₂ ^* are used as calculation elements to calculate a vehicle traveling state.

(Operation) When there is no difference between the left and right wheel rotational accelerations ₁ and ₂ , the actual wheel rotational speeds W ₁ and W ₂ are calculated as left wheel rotational speed W ₁ ^* and right wheel rotational speed W. _{As 2} ^* , the vehicle state calculating means g calculates the vehicle states such as the turning radius, the vehicle speed, the yaw rate, and the centripetal acceleration by calculation.

If there is a difference between the rotational accelerations ₁ and ₂ of the left and right wheels,
It is estimated by the first correction means e that slip has occurred on the wheel on the side where the rotational acceleration is large, and there is little or no wheel slip, based on the rotational speed on the side where the rotational acceleration is small, The wheel rotation speed on the side where the rotation acceleration is large is corrected.

That is, by removing the influence of the detection error due to the wheel slip, the values obtained by the correction of the direction that results in a more accurate wheel rotation speed value are calculated as the left wheel rotation speed W ₁ ^* and the right wheel rotation speed W ₂ ^* . The vehicle state calculating means g accurately calculates the vehicle states such as the turning radius, the vehicle speed, the yaw rate, and the centripetal acceleration.

When the difference between the rotational accelerations ₁ and ₂ of the left and right wheels returns to a difference within a predetermined value after the correction is performed by the first correction means e, the wheel rotational speeds W ₁ and W ₂ are returned to the actual wheel rotational speeds at once. Instead, the second correction means f makes a correction to gradually match the value obtained by the correction with the actual wheel rotation speeds W ₁ and W ₂ , and this value is calculated as the left wheel rotation speed.
As W ₁ ^* and right wheel rotation speed W ₂ ^* , vehicle state calculation means g
In the above, the vehicle radius, turning speed, yaw rate, centripetal acceleration, etc. are calculated as values that do not cause sudden changes in the vehicle state.

Therefore, even when the slip ratio on one side increases, such as when traveling on a low friction coefficient road or when turning with a large centripetal acceleration,
Accurate vehicle status input information can be provided, and even if the correction is completed immediately after the one-wheel slip has converged and the left / right wheel rotation speed difference has not become normal, the vehicle status input information can be changed suddenly. Without, it is possible to bring accurate vehicle state input information.

(Examples) Hereinafter, examples of the present invention will be described in detail with reference to the drawings. In describing this embodiment, the vehicle running state applied to a rear wheel drive vehicle-based four-wheel drive vehicle equipped with a drive force distribution control device that changes the drive force distribution to the front wheels according to the vehicle running state Take a computing device as an example.

First, as shown in FIG. 2, the vehicle running state calculation device A of the embodiment has a left front wheel speed sensor (left wheel rotation speed detecting means).
1, a right front wheel speed sensor (right wheel rotation speed detection means) 2, a module (left and right wheel acceleration calculation means, first and second correction means, vehicle running state calculation means) 3.

The left and right front wheel speed sensors 1 and 2 are sensor rotors 11 and 21 that rotate in synchronization with the front wheels 4 and 5 that are driven according to the fastening force of the transfer clutch 6, and the sensor rotors 11 and 21 that are fixed to the vehicle body side. 21 formed serration teeth 11a, 21a
And sensor pickups 12 and 22 arranged close to each other.

As shown in FIG. 3, the sensor pickups 12 and 22 have permanent magnets 12a and 22a and coils 12b and 22b built therein. When the sensor rotors 11 and 21 rotate, the sensor pickups 12 and 22 are Magnetic flux m by the permanent magnets 12a, 22a of
The sensor pickup 1 changes when the gap between the serration teeth 11a, 21a and the tip of the sensor pickup 12, 22 changes.
Electromagnetic induction electromotive force is generated in the coils 12b and 22b in the coils 2 and 22 by a sine wave voltage signal having a frequency corresponding to the number of revolutions of the sensor rotors 11 and 21 (Fig. 4a).

This electromagnetic induction electromotive force is sent to the module 3 as a left front wheel rotation speed signal (wf ₁ ) and a right front wheel rotation speed signal (wf ₂ ), respectively.

The module 3 converts the left front wheel rotation speed signal (wf ₁ ) and the right front wheel rotation speed signal (wf ₂ ) based on the sine wave voltage signals sent from the both wheel bundle sensors 1 and ₂ into rectangular wave signals (pulse signals), respectively. Based on the waveform shaping circuit for conversion (FIG. 4b), the left front wheel rotation speed Wf ₁ and the right front wheel rotation speed Wf ₂ obtained by the pulse period, the turning radius R, the vehicle speed V,
This is an electronic control circuit centered on a microcomputer that calculates the yaw rate and centripetal acceleration Yg by calculation.

Reference numeral 7 in the drawing is a drive force distribution control device, which controls the engagement force of the transfer clutch 6 based on the input information from the module 3.

 Next, the operation will be described.

First, the flow of the vehicle travel calculation processing operation in the module 3 will be described with reference to the flowchart shown in FIG.

In step 100, the left front wheel rotation speed Wf ₁ and the right front wheel rotation speed Wf ₂ are read by the left front wheel rotation speed signal (wf ₁ ) and the right front wheel rotation speed signal (wf ₂ ) from the vehicle wheel speed sensors ₁ and ₂ .

In step 101, the left front wheel rotation speed W read this time
and f ₁ and the right front wheel rotational speed Wf _2, the rotational speed variation [Delta] W ₁ in a single processing cycle of the left front wheel rotational speed Wf ₁₀ and the right front wheel rotational speed Wf ₂₀ read last, [Delta] W ₂ is calculated . The calculation formula is as follows.

ΔW ₁ = Wf ₁ −Wf ₁₀ ΔW ₂ = Wf ₂ −Wf _{20 In} step 102, the rotational accelerations ₁ and 2 of the left and right wheels are calculated by the rotational speed changes ΔW ₁ and ΔW ₂ obtained in step 101 and the calculation processing cycle t ₀ . ₂ is required.

The calculation formula is as follows. ₁ = ΔW ₁ / t _{0 2} = ΔW ₂ / t _{0 In} step 103, the rotational acceleration difference Δ is calculated from the rotational accelerations ₁ and ₂ of the left and right wheels calculated in step 102.

 The calculation formula is as follows.

Delta = ₂ - ₁ in step 104 and step 105, step 103
The rotational acceleration difference Δ obtained in
_It is judged whether it exceeds ₀ (step 104) or is less than the set rotational acceleration difference −Δ ₀ (step 105). If both steps 104 and 105 satisfy Δ> Δ ₀ , Δ
<−Δ ₀ , _{3 in} the case of −Δ ₀ ≦ Δ ≦ Δ ₀
Left and right wheel rotation speeds W ₁ ^* , W ₂ for different calculations depending on the street
^* Is set.

If Δ> Δ _0, the routine proceeds to step 106, where it is determined that the right front wheel 5 has a drive slip tendency, and the right wheel rotational speed W ₂ ^* for calculation is the right wheel rotational speed W ₂₀ ^* one cycle before, The correction calculation is performed by adding the change ΔW ₁ of the left wheel rotation speed in step 101.

Therefore, at step 106, the left wheel rotation speed Wf ₁ obtained by the detection is set as it is as the left wheel rotation speed W ₁ ^* for calculation, and the value obtained by the calculation of (W ₂₀ ^* + ΔW ₁ ) is the right wheel for calculation. It is set as the wheel rotation speed W ₂ ^* .

When Δ <−Δ _0, the routine proceeds to step 107, where it is determined that the left front wheel 4 is in a drive slip tendency, and the left wheel rotational speed W ₁ ^* for calculation is set to the left wheel rotational speed W ₁₀ ^* one cycle before. The correction calculation is performed by adding the right wheel rotation speed change amount ΔW ₂ in step 101.

Therefore, in step 107, the value obtained by the calculation of (W ₁₀ ^* + ΔW ₂ ) is set as the left wheel rotation speed W ₁ ^* for calculation, and the right wheel rotation speed Wf ₂ obtained by the detection is directly used for the calculation right wheel. It is set as the wheel rotation speed W ₂ ^* .

-If Δ ₀ ≤ Δ ≤ Δ ₀ , the left and right front wheels 4,5
Determines that the occurrence of the drive wheel slip is not large in any case, the process proceeds to step 108, and it is determined whether or not the correction flag FLAG · H = 1, and when FLAG · H = 0, step 109
The left and right wheel rotation speeds Wf ₁ and Wf ₂ obtained by the detection are set as they are as the left and right wheel rotation speeds W ₁ ^* and W ₂ ^* for calculation.

When either of the steps 106 and 107 for setting the left and right wheel rotation speeds W ₁ ^* , W ₂ ^* for correction by correction has elapsed,
Proceeding to step 110, the correction flag FLAG · H = 1 is set, and the left and right wheel rotation speeds W ₁ ^* , W ₂ ^* for calculation are set by the left and right wheel rotation speeds Wf ₁ , wf ₂ obtained by the detection step 1
If 09 has passed, proceed to step 111, where the correction flag F
Set LAG · H = 0.

Then, in step 112, the left and right wheel rotation speeds Wf ₁ and Wf ₂ are set.
It is stored as Wf ₁₀ and Wf ₂₀ , and in step 113, each vehicle state is calculated based on the left and right wheel rotation speeds W ₁ ^* and W ₂ ^* for calculation.

In addition, turning radius R, vehicle speed V, yaw rate, centripetal acceleration Yg
The arithmetic expression of is as follows.

V = {1/2 * ( W 1 * + W 2 *)} / r = K1 · | W 1 * -W 2 * | R = V / = K2 | (W 1 * + W 2 *) / (W 1 * −W ₂ ^* ) | Yg = V ₂ / R = K3 | (W ₁ ^* + W ₂ ^* ) * (W ₁ ^* −W ₂ ^* ) | where K1, K2, K3 are proportional constants determined by vehicle specifications, r
Is the tire radius.

Further, when the correction flag FLAG · H = 1 is set by the passage of the step 110 and the slip is converged and it is judged YES in step 108, the process does not proceed to step 109 but the step 109. The process proceeds to the second correction processing step 114 to step 125.

In step 114, deviations Δf ₁ and Δf ₂ between the measured wheel speeds Wf ₁ and Wf ₂ and the calculation wheel speeds W ₁₀ ^* and W ₂₀ ^* one cycle before are calculated.

 The calculation formula is as follows.

Δf ₁ = Wf ₁ −W ₁₀ ^* Δf ₂ = Wf ₂ −W ₂₀ ^{* In} steps 115 to 118, are the deviations Δf ₁ and Δf ₂ obtained in step 114 within the set deviations A ₁ and −A ₂ ? If it is judged that the deviations Δf ₁ and Δf ₂ are larger than the set deviation A ₁ , that is, if the measured value is larger than the calculated value one cycle before, the set deviation A ₁ is gradually added in steps 119 and 121. It increases and approaches the measured value. Also,
When the deviations Δf ₁ and Δf ₂ are smaller than the set deviation −A ₂ , that is, when the calculated value one cycle before is larger than the actual measured value, the set deviation −A ₂ is gradually decreased in Steps 120 and 122. Bring it closer to the measured value.

In step 123, since the correction is performed in all of steps 119 to 122, the correction flag FLAG · H
Set to 1.

Then, when the deviations Δf ₁ and Δf ₂ are −A ₂ ≦ Δf ₁ and Δf ₂ ≦ A ₁ , and the calculated value one cycle before and the measured value substantially match, the routine proceeds to step 124, where the measured wheel speed is Wf ₁ and Wf ₂ are calculated wheel speeds W ₁ ^* and W ₂ ^*, and correction is shown in step 125.
FLAG · H = 1 is rewritten to FLAG · H = 0 indicating the end of correction, and the process proceeds from step 112 to step 113.

Next, referring to FIG. 6, a correction situation on a straight μ road will be described.

On the split μ road, due to the influence of the driving force due to acceleration, there is a difference in rotational speed between the left and right wheels.

Then, at the point A, if the rotational speed difference suddenly increases, the rotational acceleration difference Δ between the left and right wheels exceeds the set value Δ ₀ , so the first correction processing in steps 100 to 113 is executed to rotate the left wheel. The speed is corrected.

Further, when the point D at which the rotational acceleration difference Δ between the left and right wheels decreases, and the value becomes within the set value Δ ₀ at this position, step 11
The second correction process in steps 4 to 125 is executed, and the calculation left wheel rotational speed W ₁ ^* gradually increases at every A ₁ step, and the left and right wheel rotational speed difference also gradually increases to reach point C.

In other words, in the present embodiment, the correction process of A point → (first correction) → B point → (second correction) → C point is performed, so that A point → B point → D point → C point. It is possible to prevent a sudden change in the wheel speeds for calculation W ₁ ^* , W ₂ ^* , which is the case in the prior art in which the correction process reaches the maximum.

As described above, the vehicle running state calculation device of the embodiment has the following effects.

Since the vehicle running state is obtained using the rotational speeds Wf ₁ and Wf ₂ of the left and right front wheels 4 and 5, it is not necessary to make corrections such as slip angles as when obtaining the vehicle running state using the steering angle. An accurate vehicle traveling state based on the actual turning situation can be calculated.

The left and right front wheel rotation speed sensors 1 and 2 are used as input sensors in vehicles equipped with an anti-skid control device that prevents wheel lock during braking, a traction control device that controls wheel driving force, etc. It is possible to obtain the vehicle traveling state as new control information at low cost by sharing the sensor without additional addition.

The wheel slip situation is judged by the rotational accelerations ₁ and ₂ of the left and right wheels, and the left wheel rotational speed W ₁ ^* obtained by the first correction processing in which the influence of the detection error due to the wheel slip is removed ^.
Also, since the right wheel rotation speed W ₂ ^* is used as a calculation element, the vehicle state such as the turning radius R, the vehicle speed N, the yaw rate, and the centripetal acceleration Yg can be accurately calculated.

Therefore, even when the slip ratio on one side increases, such as when traveling on a low friction coefficient road or when turning with a large centripetal acceleration,
Accurate vehicle status input information is provided.

The rotational acceleration difference Δ between the left and right wheels is the set rotational acceleration difference Δ
_Since it is a device that corrects when it exceeds ₀ , the rotational speed is not corrected by the difference in rotational acceleration that occurs during turning without slip, and the calculation accuracy of the vehicle state during turning without slip is ensured. You can do it.

Since the correction wheel rotation speed on the side with large rotation acceleration is obtained by adding the increase in rotation speed on the side with small rotation acceleration to the wheel rotation speed one cycle before, As the wheel rotation speed, the rotation speed increase including the slip component generated in one cycle is replaced with the rotation speed increase that does not substantially include the slip component, so that the highly accurate left wheel rotation speed W ₁ ^{* And} right wheel rotation speed W ₂
You can get ^* .

After the first correction process is executed, when the difference between the rotational accelerations ₁ and ₂ of the left and right wheels returns to a difference within a predetermined value, the actual wheel rotation speeds W ₁ and W ₂ are not immediately returned. , the second correction processing by the first correction processing is gradually corrected to match the obtained actual wheel rotational speeds W ₁ value, W ₂ in is performed, the left wheel rotational speed W ₁ and this value is an arithmetic element ^Since the vehicle state (turning radius, vehicle speed, yaw rate, centripetal acceleration, etc.) is calculated as ^* and the right wheel rotation speed W ₂ ^* , the vehicle state value does not suddenly change.

Therefore, immediately after the one-wheel slip has converged when traveling straight on a split μ road or the like, even if the first correction processing is finished before the difference in the left and right wheel rotation speeds becomes normal, the vehicle state input information is suddenly changed. It is possible to bring accurate vehicle state input information without any need.

The embodiment of the present invention has been described in detail above with reference to the drawings.
The specific configuration is not limited to this embodiment, and is included in the present invention even when there is a design change within the range not departing from the gist of the present invention.

For example, in the embodiment, the example in which the rotation speed detecting means is provided to the left and right front wheels to which the driving force is distributed by the engagement of the transfer clutch is shown. However, since the rotation speed with high accuracy can be calculated by the correction, It can be applied regardless of the driving wheel.

Further, as an application example of this vehicle traveling state calculation device,
The applicant previously proposed Japanese Patent Application No. Sho 61-82834 (Japanese Patent Publication No.
No. 026938), it is not limited to the operation limiting amount control device and the driving force distribution control device described in the publication, but other drive system control, anti-roll control by the suspension device, and anti-spin control by the rear wheel steering device. Of course, it can be applied to control and the like.

(Effects of the Invention) As described above, in the vehicle traveling state calculation device of the present invention, the rotational acceleration of the left and right wheels is determined based on the rotational speed of the rotational acceleration on the side with the smaller rotational acceleration. First correction means for correcting the wheel rotation speed, and the first correction means.
Second correction means for gradually matching the actual wheel rotation speed after the correction by the correction means, and the first and second correction means.
When it is corrected by the correction means described above, the apparatus is provided with a vehicle running state calculation means for calculating the vehicle running state using the left wheel rotation speed and the right wheel rotation speed obtained by including the corrected rotation speed as calculation elements. , Turning radius, vehicle speed, yaw rate,
The vehicle state such as the centripetal acceleration is accurately calculated, and even when the slip ratio on one side increases, such as when traveling on a low friction route or when turning with a large centripetal acceleration, the accuracy of the first correction process It is possible to provide good vehicle state input information, and immediately after the one-wheel slip has converged, the vehicle state input information is suddenly changed even if the first correction process is completed before the difference between the left and right wheel rotation speeds becomes normal. It is possible to obtain the effect that the vehicle state input information with high accuracy can be provided without performing the above.

[Brief description of drawings]

FIG. 1 is a diagram corresponding to the claims showing a vehicle running state calculation device of the present invention, FIG. 2 is a diagram showing a vehicle running state calculation device of an embodiment, and FIG. 3 is an explanatory diagram of a detection principle of a wheel speed sensor of the embodiment device. FIG. 4 is a diagram showing a sine wave voltage signal from a wheel speed sensor and a pulse signal from a waveform shaping circuit, FIG. 5 is a flow chart diagram showing an arithmetic processing routine of a vehicle running state, and FIG. 6 is a split μ straight road. It is a time chart figure explaining the amendment operation at time. a: left wheel rotational speed detecting means b: right wheel rotational speed detecting means c: left rotational acceleration calculating means d: right rotational acceleration calculating means e: first correcting means f: second correcting means g ...... Vehicle running state calculation means

Claims (2)

[Claims] 1. A left wheel rotation speed detection means and a right wheel rotation speed detection means for respectively detecting rotation speeds of the left and right wheels, and an increase / decrease of the left wheel rotation speed and the right wheel rotation speed detected by the detection means. Of the left wheel rotational acceleration calculation means and the right wheel rotational acceleration calculation means, which respectively calculate the rotational acceleration, and the left and right wheel rotational accelerations obtained by the calculation means,
First correction means for correcting the wheel rotation speed on the side with a large rotation acceleration based on the rotation speed on the side with a small rotation acceleration, and after the correction by the first correction means is executed, the actual wheel rotation speed is obtained. The vehicle traveling using the second correction means for gradually matching and the left wheel rotation speed and the right wheel rotation speed obtained by including the corrected rotation speed when corrected by the first and second correction means. A vehicle running state computing device comprising: a vehicle running state computing means for computing a state. 2. The first correcting means is a means for correcting when the difference between the rotational accelerations of the left and right wheels exceeds a set value, and the second correcting means is executed by the first correcting means. The vehicle running state calculation device according to claim 1, further comprising means for performing correction when the difference between the rotational accelerations of the left and right wheels returns to within a set value.