JPS61247556A - Anti-skid control device - Google Patents

Abstract

PURPOSE:To make it possible to control the anti-skid operation of a vehicle with a high degree of accuracy, by estimating the frictional coefficient (mu) of a road surface in accordance with the difference between the peak value of false speed of the vehicle body and the last time peak value, and the lapse time thereof so that the deceleration of the wheel speed and the detected level of slips are changed in accordance with the frictional coefficient. CONSTITUTION:A selecting means 6 detects the highest one among outputs from vehicle wheel detecting means 5a through 5c for detecting the speeds of wheels 1a through 1c. Further, a false vehicle body speed subtractor 7 subtracts a predetermined amount from a false vehicle speed one control period before, and a false vehicle speed determining means 8 compares the output of the subtractor 7 and the output of the selecting means 6 to determine the higher one as a false vehicle body speed. Then, a road surface frictional coefficient (mu) estimating means 9 detects the peak value of the false vehicle body speed to obtain the deceleration of the vehicle body in accordance with the difference between the present peak value and that of the last time and the lapse time thereof, the thus obtained value being determined as the frictional coefficient(mu) of the road surface. Further, the anti-skid control is changed to exhibit such a trend that the lower the frictional coefficient (mu) of the road surface, the lower the braking pressure becomes.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention reduces the braking pressure by operating a 7-cut unit when the wheels are about to lock during braking, and when the wheel rotation returns due to this pressure reduction, the braking pressure is restored again. The present invention relates to an anti-skid control device that avoids a locked state of the wheels by repeatedly applying pressure and repeating this operation.

[Conventional technology]

Conventionally, in anti-skid control, braking pressure is accelerated or decelerated based on the amount of lag between the acceleration/deceleration of wheel speed and the pseudo vehicle speed. However, these detection levels are independent and constant even when μ (friction coefficient) of the road surface changes, and this cannot be said to be accurate control. There is also a device equipped with a deceleration sensor to measure the deceleration of the vehicle body and used to estimate the road surface μ. The control details were not accurate, and a special sensor was required to estimate the road surface μ.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to obtain an anti-skid control device that can perform anti-skid control more accurately on all road surfaces.

[Means for solving problems]

During anti-skid control, the road surface μ is estimated based on the difference between the peak value of the pseudo vehicle speed and the previous peak value and the elapsed time t, and the detection level of wheel speed deceleration and slip amount is determined based on the road surface μ value. I tried to control it by changing it.

[For production]

By estimating the road surface μ, it is possible to perform precise and precise control appropriate to the road surface μ.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

In FIG. 1, 1a is the right front wheel, 1b is the left front wheel, 1c is the rear wheel, 2 is a sentence control circuit with a built-in microcomputer,
3a to 3C, each wheel 1 is controlled by a drive signal from the control circuit 2, respectively.
Actuators 4 and 4C are actuators that reduce and increase the braking pressure for a to IC, and brakes that brake the wheels 1a to ICt, respectively. In the control circuit 2, there are wheel speed detection means 5a to 5C for detecting the driving wheel speeds of the respective wheels 1a to IC, respectively, and select high selection means 6 for selecting the highest speed among the respective wheel speeds.
, a pseudo vehicle speed subtracter 7 that subtracts a predetermined amount from the pseudo vehicle speed one control cycle before, a pseudo vehicle speed subtracter 7 that compares the output of the subtracter 7 with the output of the select high selection means 6, and sets the higher speed as the pseudo vehicle speed. Vehicle speed determination means 8 detects the peak value of the pseudo vehicle speed;
A road surface noise estimating means 9 calculates the individual deceleration from the difference from the previous peak value and the time elapsed during that time and estimates this as the road surface μ, and performs so-called anti-skid control using each wheel speed, pseudo vehicle speed, and road surface μ. Anti-skid control judgment that changes the control so that the braking pressure tends to be reduced depending on the value of the road surface μ, and outputs drive signals for the actuators 3a to 3c. Means 10 are provided.

Further, FIG. 2 shows a more specific configuration of this embodiment, in which rear wheel brakes 4c, 1 for the right rear wheel and 4c2 for the left rear wheel are provided. The companion control circuit 2, which has a built-in microcomputer, calculates the speed of each wheel based on the control program, determines a pseudo vehicle speed, and detects when the vehicle is about to lock up through deceleration control based on wheel speed, slip amount control, or a combination thereof. Outputs drive signals to various actuators. If the signal is a pressure reduction request, 3ax for the right front wheel and 3b for the left front wheel.
1. Activate each pressure reducing actuator for rear wheel 3c1,
Conversely, if pressure recovery is required, 3a2 for the right front wheel and 3b2 for the left front wheel.
, actuate each pressure actuator for rear wheel 3c2.

On the other hand, the braking pressure is constantly increased from a storage chamber 11 containing braking fluid by a motor 12 etc. that is connected to a device for detecting a decrease in braking pressure, and is stored in a pressure accumulator 13. When the braking pressure is in the pressurized state, the pressurizing actuators 3a2, 3b2, 3
c2 t-through) Each brake 4a to 4cK is supplied, and in the case of a reduced pressure state, pressure reducing actuators 3'al to 3c1 are supplied.
It passes through and returns to storage room 11. Pressure adjustment actuator 3
If both valves a to 3c are not operating, the current braking pressure is maintained.

14 is 6 with the brake pedal.

Next, the operation of the control circuit 2 incorporating the microcomputer will be explained using the flowchart shown in FIG. first,
After starting and initializing in step S1, the wheel speed VFR of the right front wheel is calculated in step S2. The calculation method is as follows: P is the friend wheel speed/9rus number input within a certain period, and is the time t when the nogle is input for the first time after starting the measurement.
There is a period measurement method in which Tt, the final Noculus is input, and the next time t-Tn is determined by the following formula. Here, K is a constant. In step S3, the wheel speed VFL of the front left wheel is similarly calculated, and in step S4, the wheel speed VRt- of the rear wheel is calculated. In step S5, the highest wheel speed SH (select high) is selected from among the respective wheel speeds. In STELLA fs6, a predetermined amount α is subtracted from the pseudo vehicle speed Vps one control period before, and a new pseudo vehicle speed Vpat- is calculated. Step S7
Now let's compare the pseudo vehicle speed VPN and Select High 5Ht. If VPN<SH, the value of SH is substituted into the pseudo vehicle speed VPH in step S8. In step S9, road surface μ is calculated from this pseudo vehicle speed. In step S10, so-called anti-skid control is determined for the right front wheel. As a control method, the acceleration/deceleration of the wheel speed VFil is calculated, and when a deceleration of a predetermined value of 1 or more is detected, the decompression mode is set, and when the acceleration of a predetermined value or more is detected, the pressurization mode is set.Deceleration control There is.

In addition, the difference between the pseudo vehicle speed VPN and the wheel speed, that is, the amount of slip, is calculated, and when a slip amount greater than a predetermined value C is detected, the pressure reduction mode is selected, and when the slip amount is less than a predetermined value d, the pressure mode is selected. There is quantity control. Furthermore, there is also a type that combines deceleration control and slip amount control. or,
Predetermined values a, b, c which are detection levels depending on the value of road surface μ
, d@ change to make the control sound more detailed. Road surface μ is Oku μ
The values of a, b, c, and d are set to be larger in the high μ road than in the low μ road. Then, when it is determined that the mode is the pressure reduction mode, a signal for driving the pressure reduction actuators 3a1 to 3cl is outputted in Stella 7'S11. Further, if it is determined that the pressurization mode is selected, a signal for driving the pressurization actuators 3a2 to 3c2 is outputted in step S12. If the current braking pressure is maintained or the anti-skid state is not present, that is, the normal braking state is present, the signal is stopped at Stella 7'S13 so as to deactivate both actuators 3a to 3c.

The same thing that was done for this Stella fs10-813 was done for the left front wheel in gold step 814, and Stella 7
'S15 is executed for the rear wheels.

When step S15 ends, the process returns to step S2 again.
The following steps are executed.

Next, a method of calculating the road surface μ will be explained based on FIG. 4. Break Iw20 is the wheel speed data of the select high SH, and it changes as shown. This select high SH
Based on this, the pseudo vehicle speed VPN changes as shown in the actual 1!21. Therefore, when it is checked whether the pseudo vehicle body speed VPN is the same value as the select high SH (during tracking), a track signal 22 is obtained. Further, a signal 23 is obtained by checking whether the pseudo vehicle speed has decreased compared to one control cycle ago, that is, by checking the sign of the differential. Here, the first value at which both signals 22 and 23 are outputted is set as the peak value of the pseudo vehicle speed, and the time at this time is also stored. Note that point A is the pseudo vehicle speed when anti-skid control is entered for the first time. Then, the deceleration of the vehicle body can be found using the formula. This single deceleration is considered to be almost the same as the road surface μ, so the road surface μ can be found using a formula that takes into account the constant N. The next calculation of road surface μ is performed using point B and point 0 instead of point A and point 0 in order to quickly respond to changes in road surface μ.

〔Effect of the invention〕

As described above, according to the present invention, the coefficient of friction of the road surface is estimated from the simulated vehicle speed, and the braking pressure is controlled to be small on the road surface where this value is low. Easy to control.

[Brief explanation of the drawing]

1 and 2 are a block diagram and a specific configuration diagram of the device of the present invention, FIG. 3 is a flowchart showing the control operation of the device of the present invention, and FIG. Here is an explanatory graph that calculates . 1a-IC...wheel, 3a-3C...pressure adjustment actuator, 4a-4C...brake device, 5a-5C...
Wheel speed, 6... Select high selection means, 7... Pseudo vehicle speed subtractor, 8... Pseudo vehicle speed determining means, 9...
Road surface μ estimating means, 10...Anti-skid control determining means. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Claims] (1) When the wheels are about to lock up during braking, the brake pressure is reduced by actuating the actuator, and when the wheels return to rotation due to this pressure reduction, the braking pressure is restored again, and this operation is repeated to avoid the wheel lock condition. An anti-skid control device for safely braking a vehicle, comprising two or more wheels, an actuator for reducing or increasing the braking pressure of each wheel, and a brake for braking each wheel, respectively;
A wheel speed detection means for detecting each wheel speed, a select high selection means for selecting the highest speed among each wheel speed, and a pseudo vehicle speed subtractor for subtracting the pseudo vehicle speed one control period before by a predetermined amount; A pseudo vehicle speed determining means compares the output of the pseudo vehicle speed subtracter and the output of the select high selection means and sets the higher speed as the final pseudo vehicle speed, and detects the peak value of this pseudo vehicle speed and compares it with the previous peak value. and a road surface friction coefficient estimating means that estimates the road surface friction coefficient from the difference between and the elapsed time, and determines anti-skid control based on each wheel speed, pseudo vehicle speed, and road surface friction coefficient. An anti-skid control device comprising anti-skid control determining means for outputting a drive signal to an actuator so as to reduce braking pressure.