JPH068815A - Target slip ratio correcting device - Google Patents

Abstract

PURPOSE:To provide a target slip ratio correcting device capable of maintaining a smooth running condition of a vehicle according to a variation in road surface conditions. CONSTITUTION:In a target slip ratio correcting device 30, a road surface friction coefficient is calculated in a road surface friction coefficient calculation circuit 32 based on outputs from sensors 18, 20, and 22 and, according to a variation ratio of the road surface friction coefficient, a correction coefficient is calculated in a correction coefficient decision circuit 34. Also a target slip ratio is set up in a target slip ratio calculation circuit 40 based on the road surface friction coefficient value, and the target slip ratio is set up and multiplied by the correction coefficient to correct the target slip ratio. Thus, even if road surface condition is varied largely, a good traveling condition of a vehicle can be maintained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a target slip ratio correction device which is mounted on a motorcycle, an automobile or the like and corrects a target slip ratio capable of giving an optimum braking force or driving force to a vehicle body. .

[0002]

2. Description of the Related Art In automobiles and motorcycles, for example, a so-called brake control device is used which controls the wheel speed of a vehicle being braked by comparing it with the vehicle speed. In this brake control device, the slip ratio is obtained from the wheel speed and the vehicle body speed, and when the slip ratio becomes equal to or higher than the target slip ratio for optimal braking, the brake fluid pressure is reduced to control the wheel speed and slip. The ratio is reduced to obtain a good braking force. In this case, the target slip ratio is set according to the friction coefficient of the road surface.

[0003]

By the way, on an actual traveling road, the road surface friction coefficient μ may change significantly with changes in road surface conditions. For example, a slip state is different between a road surface having a low friction coefficient such as ice burn (hereinafter referred to as a low μ road) and a road surface having a high friction coefficient such as an asphalt road (hereinafter referred to as a high μ road). Therefore, for example, when the target slip ratio is changed with respect to a road surface (so-called μ-jump road surface) in which the road surface condition changes from a low μ road to a high μ road, vibration is generated to increase the fluctuation range of the braking force. There is a problem that the brake feeling deteriorates. As a method for solving this problem, a method has been proposed in which modulation control of the braking force of the front and rear wheels is individually performed as in Japanese Patent Laid-Open No. 62-194963, but the braking force fluctuates with a sudden change in the road surface μ. There was a problem that the width became large.

The present invention has been made in order to solve this kind of inconvenience, and provides a target slip ratio correction device capable of maintaining a smooth running state of a vehicle body against changes in road surface conditions. The purpose is to

[0005]

In order to achieve the above-mentioned object, the present invention is a device for correcting a target slip ratio for controlling a braking force or a driving force of a vehicle, which comprises a wheel rotation speed and a vehicle body. Road surface friction coefficient calculation means for calculating a road surface friction coefficient from acceleration / deceleration, change rate calculation means for obtaining a change rate of the road surface friction coefficient, and correction coefficient storage means for storing a correction coefficient of a target slip rate for the change rate. And a target slip ratio set in advance is corrected based on the correction coefficient.

[0006]

In the target slip ratio correction device according to the present invention, the change rate of the road surface friction coefficient calculated by the road surface friction coefficient calculation means is obtained, and the correction coefficient of the target slip ratio stored in the correction coefficient storage means is used as the change rate. And the target slip ratio is corrected based on the correction coefficient. Therefore, even when the road surface friction coefficient changes significantly (μ-jump road surface), the target slip ratio is not significantly changed by the correction coefficient, so that the braking force is not significantly increased or decreased, and it is good. Maintain a good running condition.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A target slip ratio correction device according to the present invention will be described in detail below with reference to the accompanying drawings with reference to preferred embodiments.

First, as a first embodiment, the road surface friction coefficient μ
A target slip ratio correction device that corrects the target slip ratio S0 based on the change rate will be described.

In FIG. 2, reference numeral 10 indicates a motorcycle, and the motorcycle 10 includes a main body portion 12, a front wheel portion (driven wheel) 14 and a rear wheel portion (driving wheel) 16. The front wheel portion 14 and the rear wheel portion 16 are respectively provided with a driven wheel rotation speed detection sensor 18 and a driving wheel rotation speed detection sensor 20 each including a rotary encoder and the like, and a body acceleration / deceleration detection sensor 22 in the main body portion 12. Is provided. The sensors 18, 20, 22 are connected to a control unit 24, and these constitute a target slip ratio correction device 30 shown in FIG.

The control unit 24 includes a driven wheel rotational speed detection sensor 18 and a drive wheel rotational speed detection sensor 2.
From the output signal of 0, the wheel rotation speed and the wheel rotation acceleration / deceleration of the front wheel portion 14 and the rear wheel portion 16 are obtained, and the vehicle body acceleration is obtained from the output signal of the vehicle body acceleration / deceleration detection sensor 22. A road surface friction coefficient calculation circuit 32 that calculates an estimated vehicle speed and a slip rate and obtains a road surface friction coefficient μ of each wheel based on the slip rate and the vehicle body acceleration / deceleration, and a change rate of the road surface friction coefficient μ A correction coefficient determination circuit 34 that determines the correction coefficient ηj of the slip ratio S0, and a look-up table (hereinafter referred to as LUT) 36 that stores a table that determines the correction coefficient ηj according to the change rate of the road surface friction coefficient μ.
And a road surface friction coefficient storage circuit 38 for storing the road surface friction coefficient μ calculated last time, and a target slip ratio calculation circuit 40 for correcting the target slip ratio S0 from the road surface friction coefficient μ and the correction coefficient ηj. Prepare

First, how to obtain the correction coefficient ηj for the target slip ratio S0 on the driven wheel (front wheel portion 14) side will be described with reference to FIG. The correction coefficient ηj of the driven wheel and the driving wheel can be independently calculated. The target slip ratio correction device 30 obtains the correction coefficient ηj (n) as follows at every predetermined calculation cycle t. here,
(N) indicates a value in the n-th calculation.

First, while the motorcycle 10 is running,
Driven wheel rotation speed detection sensor 18 disposed on the front wheel portion 14
Detects the rotation of the driven wheel (front wheel portion 14) as a pulse signal and outputs it to the road surface friction coefficient calculation circuit 32. Further, the vehicle body acceleration / deceleration detection sensor 22 outputs the vehicle body acceleration / deceleration to the road surface friction coefficient calculation circuit 32. Here, in the road surface friction coefficient calculation circuit 32, the wheel rotation speed and the wheel rotation acceleration / deceleration are obtained based on the signal from the driven wheel rotation speed detection sensor 18, and the vehicle body acceleration / deceleration based on the signal from the vehicle body acceleration / deceleration detection sensor 22. An estimated vehicle speed and slip rate are obtained from the speed and the wheel rotation speed. Then, the road surface friction coefficient μ (n) is obtained based on the slip ratio and the vehicle body acceleration / deceleration on the opposite side (rear wheel portion 16 side). In this case, since the vehicle body acceleration / deceleration is proportional to the road surface friction coefficient μ of the entire vehicle body, the road surface friction coefficient μ (n) of the front wheel portion 14 is obtained by subtracting the braking amount of the rear wheel portion 16 on the opposite side. The road surface friction coefficient μ (n) thus obtained is used as the correction coefficient determination circuit 3
4 and the road surface friction coefficient storage circuit 38 and the target slip ratio calculation circuit 40, respectively.

The correction coefficient determination circuit 34 reads the road surface friction coefficient μ (n-1) obtained by the previous calculation from the road surface friction coefficient storage circuit 38, and changes the road surface friction coefficient μ, that is, μ (n ) / Μ (n−1). Then L
Based on UT36 (see FIG. 3), μ (n) / μ (n−
From the value of 1) and the value of μ (n-1), the correction coefficient ηj (n)
Ask for.

The correction coefficient ηj (n) is output to the target slip ratio calculation circuit 40.

The target slip ratio calculation circuit 40 performs the following calculation using the road surface friction coefficient μ (n).

S1 (n) = f (μ (n)) × S0 (n-1) where f (μ) is a function that changes as shown by the chain double-dashed line in FIG. 4, S0 (n-1) Is the target slip ratio calculated by the (n-1) th calculation, and S1 (n) is the temporary target slip ratio calculated by the nth calculation.

Therefore, as shown in FIG. 4, the function f (μ) representing the relationship of the slip ratios that can obtain the maximum braking force in the case of the road surface condition of the road surface friction coefficient μ (n) is set as the target slip ratio. By multiplying S0 (n-1), it is possible to set the provisional target slip ratio S1 (n) that provides the maximum braking force according to the road surface condition.

Subsequently, this temporary target slip ratio S1 (n)
Is multiplied by the correction coefficient ηj (n).

S0 (n) = k × ηj (n) × S1 (n) where k is a constant.

In this case, for example, when the vehicle body has a low μ road to a high μ road
When traveling on a road surface that changes to a road, a μ-jump road surface is formed at the turning point, and the braking force may significantly increase as shown by the broken line (arrow A) in FIG. 4, but the correction coefficient ηj
By multiplying by (n), it is possible to reduce the target slip ratio as shown by the solid line (arrow B) in FIG. 4 and prevent the braking force from changing significantly. Therefore, by obtaining the new target slip ratio S0 (n) in this way, it becomes possible to maintain smooth running of the vehicle body regardless of changes in road surface conditions.

As described above, in the target slip ratio correction device 30 of the present embodiment, the temporary target slip ratio S1 (n) at which the maximum braking force on the road surface having the road surface friction coefficient μ (n) is obtained by the function f (μ) is obtained. By obtaining it, the brake control can be performed so that the maximum braking force can be obtained according to the road surface condition, and the change rate μ (n) / μ of the road surface friction coefficient μ
When (n-1) is large, by multiplying by the correction coefficient ηj (n), it is possible to prevent the braking force of the vehicle body from changing significantly and to maintain a smooth running state of the vehicle body. Also, the rate of change of the road surface friction coefficient μ μ (n) / μ
If the table set in the LUT 36 according to (n-1) is further subdivided, smoother control becomes possible.

In this embodiment, the case of brake braking has been described, but the target slip ratio can be similarly corrected by the driving force control device.

[0023]

According to the target slip ratio correction device of the present invention, the following effects can be obtained.

That is, by correcting the target slip ratio according to the change rate of the road surface condition, it is possible to maintain a smooth running state regardless of the change of the road surface condition.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of a target slip ratio correction device according to the present invention.

FIG. 2 is an explanatory view of a motorcycle equipped with a target slip ratio correction device according to the present invention.

FIG. 3 is an explanatory diagram of a table used for determining a correction coefficient in the target slip ratio correction device according to the present invention.

FIG. 4 is an explanatory diagram of an updated state of the target slip ratio in the target slip ratio correction device according to the present invention.

[Explanation of symbols]

 10 ... Motorcycle 12 ... Body part 14 ... Front wheel part 16 ... Rear wheel part 18 ... Driven wheel rotation speed detection sensor 20 ... Drive wheel rotation speed detection sensor 22 ... Vehicle body acceleration / deceleration detection sensor 30 ... Target slip ratio correction device 32 ... Road surface Friction coefficient calculation circuit 34 ... Correction coefficient determination circuit 36 ... Look-up table 38 ... Road surface friction coefficient storage circuit 40 ... Target slip ratio calculation circuit

Claims (1)

[Claims] 1. A device for correcting a target slip ratio for controlling a braking force or a driving force of a vehicle, which comprises a road surface friction coefficient calculating means for calculating a road surface friction coefficient from a wheel rotation speed and a vehicle body acceleration / deceleration. A change rate calculation means for obtaining a change rate of the road surface friction coefficient, and a correction coefficient storage means for storing a correction coefficient of the target slip rate for the change rate are provided, and a preset target slip rate is calculated based on the correction coefficient. A target slip ratio correction device characterized by correction.