JPS61235754A - Detector for slip rate - Google Patents

Abstract

PURPOSE:To improve detection precision by finding the slit rate between a wheel and a road surface on the basis of a coefficient of correction calculated by a correction coefficient calculating means, the detection result of a detecting means, and the detection result of a noncontact ground speed sensor. CONSTITUTION:The detection result of a detecting means 1 in a state of neither acceleration nor deceleration indicates an accurate vehicle speed. The detection result of the noncontact ground speed sensor 2 varies with the distance H between the sensor 2 and road surface; and the coefficient of correction to a vehicle speed detected by the sensor 2 on the basis of the detection result of the detecting means 1 and the detection result of the sensor 2 when the vehicle is in a state of neither acceleration nor deceleration and the slit rate is detected accurately on the basis of the calculated coefficient of correction, the detection result of the detecting means 1, and the detection result of the sensor 2.

Description

[Detailed Description of the Invention] [Summary] A calculation means is provided for calculating a correction coefficient for the detection result of the non-contact ground speed sensor based on the speed of the vehicle when the vehicle is not in an acceleration/deceleration state and the circumferential speed of the wheels, The slip ratio between the wheel and the road surface is calculated based on the correction coefficient calculated by the correction coefficient calculation means, the detection result of the detection means, and the detection result of the non-contact ground speed sensor, thereby determining the slip ratio with high accuracy. Make it discoverable.

[Industrial application field]

The present invention relates to a slip rate detection device that can accurately detect the slip rate between the road surface and the wheels of a vehicle.

[Conventional technology]

If the brakes are applied on a road surface that is prone to getting wet, such as a road surface that is wet from rain or ice, the wheels may become stuck and the brakes may become ineffective. To prevent this, so-called anti-skid control is used to detect the slip rate between each wheel and the road surface and control the braking force to each wheel so that the slip rate is at an appropriate value when braking. It has been previously proposed to do so. Here, the slip rate S is defined by the following equation (1), and in the opening equation, ■ indicates the speed of the vehicle, and SV indicates the circumferential speed of the wheel.

S= (SV-V) /SV =---- (1) When performing anti-skid control as described above, it is necessary to detect the slip rate between the wheels and the road surface.
Conventionally, the slip ratio has been detected in the following manner, which has resulted in the problem that an accurate slip ratio cannot be detected and optimal anti-skid control cannot be performed.

That is, in the past, each of the four wheels of a vehicle was provided with a rotation speed hand to detect its rotation speed, and the vehicle speed was determined based on the rotation speed signals from these four rotation speed hands, which caused the risk of the wheels slipping. The detection result at half-braking or during acceleration is only an estimated value of the vehicle speed, and therefore there is a problem in that an accurate slip ratio cannot be detected.

Furthermore, in order to solve the above-mentioned problems, it has been proposed to mount a non-contact ground speed sensor having the configuration shown in FIG. 4 on a vehicle and to detect the slip ratio based on the detection result. In the figure, 41 is a photoelectric conversion element D1 to D0.
12 is a photodetector, 42 is a differential amplifier, 43 is an amplifier with a DC blocking capacitor inside, 44 is a frequency detector, and 45 is an objective lens, and these constitute the non-contact ground speed sensor. It is something that will be done. Also,
46 indicates a vehicle equipped with a non-contact ground speed sensor indicated by arrow A.
It is a road that moves in the direction.

The photodetector 41 is provided with a plurality of photoelectric conversion elements D1 to 012 adjacent to each other in the direction of arrow A, of which Dl, D
3. D5. D7. D9. Dll is connected to the 10 terminal of the differential amplifier 42, and 02. D4.06.0B, 010.
012 is connected to one terminal of the differential amplifier 42. Further, a road surface 47 of a road 46 is imaged on the light receiving surface of the photodetector 41, and the resulting output signals from each of the photoelectric conversion elements D1 to D012 are applied to ten terminals or one terminal of the differential amplifier 42. The differential amplifier 42 includes a photoelectric conversion element Di, 03.
D5. D7. D9. The signal applied from Dll and the photoelectric conversion element D2. D4. D6. D8.010.
A difference signal from the signal added from 012 is created and added to the frequency &kS unit 44 via the amplifier 43. Here, the frequency f of the output signal of the differential amplifier 42 and the vehicle speed ■
has a one-to-one correspondence as shown in the following equation (2), so the vehicle speed can be determined by detecting the frequency of the output signal of the differential amplifier 42 with the frequency detector 44. In addition, in formula (2), B is the objective lens 45
H is the distance from the road surface 47 to the light receiving surface of the photodetector 41, H is the distance from the road surface 47 to the objective lens 45, and k is a proportionality constant.

V=k -B -f/H...-(2) By using such a non-contact ground speed sensor that can detect vehicle speed without contacting the road surface, there is a risk that the wheels may slip. It is possible to obtain accurate vehicle speed even when braking or accelerating. Therefore, by performing the calculation shown in equation (1) based on the detection results of the non-contact ground speed sensor shown in FIG. It becomes possible to obtain an accurate slip ratio.

However, even if the slip ratio is determined based on the detection results of the non-contact ground speed sensor shown in FIG. 4, the following problems arise. That is, as can be seen from equation (2), the detection result of the non-contact ground speed sensor shown in FIG. 4 is the distance % between the road surface 47 and the objective lens 45! ftH, and the distance H varies depending on the number of passengers, cargo loading, etc., so the slip rate was detected based on the detection results of the non-contact ground speed sensor shown in Figure 4. However, there is a problem in that it may not be possible to obtain the correct slip ratio.

[Problem that the invention seeks to solve]

The present invention solves the above-mentioned problems, and its purpose is to always be able to accurately detect the slip ratio.

Means for Solving Problem C] In order to solve the above-mentioned problems, the present invention, as shown in the configuration diagram of FIG. The detection device includes: a detection means 1 for detecting the circumferential speed of the wheels; a non-contact ground speed sensor 2 for detecting the speed of the vehicle without contact with the road surface; and a detection means 2 for detecting the speed of the vehicle without contacting the road surface; a determining means 3 for determining whether the vehicle is in an acceleration or deceleration state; and when the determining means 3 determines that the vehicle is not in an acceleration or deceleration state, based on the detection result of the detection means 1 and the detection result of the non-contact ground speed sensor 2; a correction coefficient calculation means 4 for calculating a correction coefficient for the vehicle speed detected by the non-contact ground speed sensor 2; a correction coefficient calculated by the correction coefficient calculation means 4, a detection result of the detection means 1, and the non-contact ground speed; A slip rate calculating means 5 is provided for calculating a slip rate between the road surface and the wheels based on the detection result of the sensor 2.

[For production]

The detection result of the detection means 1 in the non-acceleration/deceleration state indicates accurate vehicle speed. Further, the detection result of the non-contact ground speed sensor 2 varies depending on the distance H between it and the road surface, but if the distance H is constant, it corresponds one-to-one with the vehicle speed.

Therefore, based on the detection result of the detection means 1 and the detection result of the non-contact ground speed sensor 2 when the vehicle is in a non-acceleration/deceleration state,
A correction coefficient for the vehicle speed detected by the non-contact ground speed sensor 2 is calculated by the correction coefficient calculation means 4, and the correction coefficient calculated by the correction coefficient calculation means 4, the detection result of the detection means 1, and the detection by the non-contact ground speed sensor 2 are calculated. By determining the slip ratio based on the results, it is possible to accurately detect the slip ratio even when the distance H changes due to changes in the number of passengers or the like.

〔Example〕

FIG. 2 is a block diagram of an embodiment of the present invention, 21 is a microprocessor, 22 is a memory, 24 is an input section, 24 is an output section, 5 is a rotation speed sensor that detects the rotation speed of the right front wheel, A rotation speed sensor detects the rotation speed of the left front wheel, a nail is a rotation speed sensor that detects the rotation speed of the right rear wheel, a rotation speed sensor detects the rotation speed of the left rear wheel, and 4 is a throttle valve (not shown). ), 30 is an opening sensor 29 that detects the opening of
a change rate detector which sets the output signal a to "1" when the rate of change in the opening of the throttle valve is equal to or greater than a predetermined value based on the detection result; 31 is a brake switch that is turned on when the brake is depressed; 32 3 is a non-contact ground speed sensor having the configuration shown in FIG. 4, 33 is an anti-skid control device, and 34 is a fuel injection control device.

Further, FIG. 3 is a flowchart showing the processing contents of the microprocessor 21, and the operation of FIG. 2 will be explained below with reference to the same figure.

When the microprocessor 21 detects that the speed of the vehicle is not zero based on the detection result of the non-contact ground speed sensor 32, it starts the process shown in the flowchart of FIG. The correction coefficient C for the vehicle speed is set to 1 (step S1). It should be noted that the process of setting the correction coefficient C is specifically performed by writing the value in a predetermined area #A of the memory 229.
Next, the microprocessor 21 controls the rotation speed sensors 25 to 25.
Based on the detection results of 28, the circumferential speed of each wheel is SVI to SV4.
is determined (step S2), and then the vehicle speed is determined based on the detection result of the non-contact ground speed sensor 32 (it is determined whether or not the vehicle is in an acceleration or deceleration state based on step S4). If NO, it is determined whether the vehicle is in a deceleration state based on whether the brake switch 31 is on or not (step S5).

If it is determined that the vehicle is neither in an acceleration state nor in a deceleration state (if both the determination results in step S4.5 are No), the wheel peripheral speed Sν1 determined in step S2 and the vehicle speed V determined in step S3 are determined. Based on this, the calculation shown in the following equation (3) is performed to obtain a correction coefficient C for the detection result of the non-contact ground speed sensor 32 (step S6), and then the correction coefficient C obtained in step S6 is stored in a predetermined area of the memory 22. Write to #A (step 37).

C=V/SVI (3) In this case, the correction coefficient C is determined based on the circumferential speed SVI of the right front wheel, but if the vehicle is not accelerating or decelerating, each Since the circumferential velocities SVI to SV4 of the wheels are all equal, it goes without saying that the correction coefficient C may be determined using the circumferential velocities SV2 to SV4 of the other wheels.

Next, the microprocessor 21 performs the calculation shown in the following equation (4) based on the vehicle speed V obtained in step S3 and the correction coefficient C obtained in step S6, and calculates the true vehicle speed V.
Find o (step S8).

VO=C-V------------(4) Next, the microprocessor 21 calculates the speed based on the circumferential speeds SVI to SV4 of each wheel determined in step S2 and the true vehicle speed Vo determined in step S8. The calculations shown in the following equations (5) to (8) are performed to calculate the slip ratio 31 between the road surface and each wheel.
~S4 is determined (step S9).

SL-(SVI-Vo) / Vo ------
(5) S2= (SV2-Vo)/Vo-
-----(6)53=(SV3-Vo)/V
o ---=-(7) S4= (SV4 Vo )
/Vo・---(8) Next, the microprocessor 21 determines whether or not the non-contact ground speed sensor is zero in step S9e (step 5IO), and the determination result is If NO, the process returns to step S2, and if the determination result is YES, the process ends. Incidentally, the anti-skid control device 33 controls the slip rate 31 to 31 applied via the output section U during braking.
Based on S4, the braking force for each wheel is controlled so that the slip ratio between each wheel and the road surface is optimized, and the fuel injection control device 34 controls the braking force to optimize the slip ratio between each wheel and the road surface. If it exceeds the limit, control such as reducing the fuel injection amount is performed. Also, step 84.5
If the judgment result is YES, the microprocessor 21
The process in step S6 and step S7 is omitted, and the process in step S8 is performed.

As described above, in this embodiment, since the correction coefficient C for the detection result of the non-contact ground speed sensor blade is determined when the vehicle is in a non-acceleration/deceleration state, the Even when the distance H between the contact ground speed sensor 32 and the road surface changes, an accurate slip ratio can always be detected.

〔Effect of the invention〕

As explained above, the present invention calculates a correction coefficient for the detection result of the non-contact ground speed sensor when the vehicle is in a non-acceleration/deceleration state, and uses this correction coefficient and the detection means (in the embodiment, the rotation speed sensor Since the slip rate between the vehicle and the vehicle on the road surface is detected based on the circumferential speed of the wheels detected by the wheel circumferential speed detected by the sensor (25 to 28, etc.) and the vehicle speed detected by the non-contact ground speed sensor, the number of occupants An advantage is that even when the number of vehicles, cargo loading, etc. change, the slip ratio can always be accurately detected. Therefore, if the present invention is applied to anti-skid control, it becomes possible to perform optimal anti-skid control.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of the present invention, Fig. 2 is a block diagram of an embodiment of the present invention, Fig. 3 is a flowchart showing the processing contents of the microprocessor 21, and Fig. 4 is a block diagram of the non-contact ground speed sensor. It is. 1 is a detection means, 2 and 32 are non-contact ground speed sensors, 3 is a judgment means, 4 is a correction coefficient calculation means, 5 is a slip ratio output means, 21 is a microprocessor, 22 is a memory, and 24 is an input section. is the output part, 25 to 28 are the rotation speed sensors, 2
9 is an opening sensor, 30 is a change rate detector, 31 is a brake switch, 33 is an anti-skid control device, 34 is a fuel injection control device, 41 is a photodetector consisting of photoelectric conversion elements D1 to 012, and 42 is a differential 43 is an amplifier, 44 is a frequency detector, 45 is an objective lens, 46 is a road, and 47 is a road surface. Patent applicant Fujitsu Ten Ltd. Representative Patent Attorney Gobe Tamamushi (1 other person) Flowch Mart No. 3 @ showing processing details

Claims (1)

[Scope of Claims] A slip ratio detection device for detecting a slip ratio between a road surface and a wheel of a vehicle, comprising: a detection means for detecting a circumferential speed of the wheel; and a detection means for detecting the circumferential speed of the wheel; a non-contact ground speed sensor that detects; a determining unit that determines whether the vehicle is in an acceleration or deceleration state; and a determination unit that determines whether the vehicle is in an acceleration or deceleration state; a correction coefficient calculation means for calculating a correction coefficient for the vehicle speed detected by the non-contact ground speed sensor based on the result and the detection result of the non-contact ground speed sensor; and a correction coefficient calculated by the correction coefficient calculation means. A slip rate calculation means for calculating a slip rate between the road surface and the wheel based on the detection result of the detection means and the detection result of the non-contact ground speed sensor. Detection device.