JPH01195168A - Trouble detector for acceleration sensor and anti-skid controller using it - Google Patents

Abstract

PURPOSE:To carry out anti-skid control correctly regardless of any fault in an acceleration sensor by finding out an estimated speed of a vehicle body and further an estimated acceleration of the same in response to an output from a wheel acceleration detecting means and comparing it with an output from an acceleration sensor. CONSTITUTION:A processing circuit 2 calculates an estimated speed of vehicle body by means of an output from a wheel speed detecting means 3, and on the basis of this estimated speed of vehicle body, an estimated acceleration of vehicle body is calculated, compared with an output from an acceleration sensor 1 to check whether the acceleration sensor 1 is faulty or not. When the acceleration sensor proves to be faulty, the processing circuit 2 employs the speed of vehicle body obtained from a wheel speed detecting means instead of the speed of vehicle body obtained form an output of the acceleration sensor 1 so as to make anti-skid control in a program same as that used in the normal operation of the acceleration sensor 1 via a hydraulic actuator 5, and a hydraulic control mechanism 6.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a device for detecting whether an acceleration sensor fixed to the body of an automobile is malfunctioning, and a failure detection device for such an acceleration sensor. The present invention relates to an anti-skid control device using an anti-skid control device.

Conventional technologyIn an anti-skid control device that calculates and calculates the estimated vehicle speed by integrating the speed from an acceleration sensor fixed to the vehicle body, and performs anti-skid control using this vehicle speed, the acceleration sensor has malfunctioned. Sometimes, it is not possible to accurately detect the acceleration of the vehicle body, and therefore the vehicle speed cannot be estimated based on the output from the acceleration sensor, which may cause malfunction of the anti-skid control. Conventionally, a device for detecting whether or not such an acceleration sensor is malfunctioning has not been realized.

Problems to be Solved by the Invention An object of the present invention is to provide a device for detecting whether an acceleration sensor for detecting acceleration of a vehicle body is malfunctioning.

Another object of the present invention is to provide an anti-skid control device that can correctly achieve anti-skid control not only when the acceleration sensor is normal but also when the acceleration sensor is malfunctioning.

Means for Solving the Problems The present invention comprises: an acceleration sensor fixed to the body of an automobile; means for detecting non-braking; means for detecting wheel speed; an estimation calculation means for calculating an estimated vehicle body acceleration based on the estimated vehicle speed; and an acceleration sensor that detects when non-braking is detected by the non-braking detecting means. This is a failure detection device for an acceleration sensor, characterized in that it includes means for comparing the estimated vehicle body acceleration determined by the estimated vehicle body acceleration and the estimated vehicle body acceleration determined by the estimation calculation means.

The present invention also provides an acceleration sensor fixed to the body of an automobile, a means for detecting non-braking, a means for detecting wheel speed, and an acceleration sensor that responds to an output from the acceleration sensor. A first vehicle speed calculation means for calculating an estimated vehicle speed by integrating the output; a second vehicle speed calculation means for calculating and estimating the vehicle speed in response to the output from the wheel speed detection means; and a non-braking detection means. and means for comparing respective outputs from the first and second vehicle body speed calculation means when non-braking is detected by the acceleration sensor failure detection apparatus.

Further, the present invention provides an acceleration sensor fixed to a vehicle body, a device for detecting failure of the acceleration sensor, means for detecting wheel speed, and detecting a failure of the acceleration sensor in response to an output of the acceleration sensor failure detection device. In this state, anti-skid control is performed based on the vehicle speed obtained by calculating the output of the acceleration sensor, and in a state where the acceleration sensor is malfunctioning, the vehicle speed obtained from the output of the wheel speed detection means is calculated based on the output of the acceleration sensor. This anti-skid control device is characterized in that it includes means for performing anti-skid control using the same program as the anti-skid control that is executed when the acceleration sensor is normal based on the vehicle body speed obtained by the vehicle speed.

Furthermore, the present invention provides an acceleration sensor fixed to a vehicle body, a device for detecting failure of the acceleration sensor, means for detecting wheel speed, and detecting that the acceleration sensor is normal in response to an output of the acceleration sensor failure detection device. In a certain state, anti-skid control is performed based on the vehicle speed obtained by calculating the output of the acceleration sensor, and in a state where the acceleration sensor is malfunctioning, the output of the wheel speed detection means is used to determine whether the acceleration sensor is normal. This is an anti-skid control device characterized in that it includes means for performing anti-skid control using a program different from the anti-skid control executed in the above state.

According to the present invention, the estimated vehicle speed is determined in response to the output from the wheel acceleration detection means, the estimated vehicle acceleration is determined based on the estimated vehicle speed, and the estimated vehicle acceleration and the thus obtained estimated vehicle speed are determined. By comparing the output of the acceleration sensor with the output of the acceleration sensor, it is possible to detect whether the acceleration sensor is malfunctioning as long as the wheel speed detection means is normal.

Furthermore, according to the present invention, the vehicle speed is estimated and determined based on the output from the acceleration sensor, and the estimated vehicle speed is calculated and estimated based on the output from the wheel speed detection means. By comparison, it is possible to detect whether the acceleration sensor is malfunctioning as long as the wheel speed detection means is normal.

Furthermore, according to the anti-skid control device of the present invention,
When it is detected that the acceleration sensor is malfunctioning, the vehicle speed obtained from the wheel speed detection means is used instead of the vehicle speed obtained by calculating the output of the acceleration sensor, and the same program as when the acceleration sensor is normal is executed. In another anti-skid control device of the present invention, when a failure occurs, anti-skid control is performed using a program different from the program that uses the vehicle body speed obtained by calculating the output of the acceleration sensor.

In this way, even when the acceleration sensor fails, anti-skid control can be correctly achieved without malfunctioning.

Embodiment FIG. 1 is a block diagram of an embodiment of the present invention. An acceleration sensor 1 is fixed to the body of an automobile. The output from this acceleration sensor 1 is input to a processing circuit 2 realized by a microcomputer or the like. The wheel speed of the vehicle's wheels is detected by the wheel speed detection means 3, and its output is given to the processing area &+82. The processing circuit 2 provides a control signal to the hydraulic actuator 5 via a line 4, whereby friction braking for anti-skid control is performed by the hydraulic braking mechanism 6 of the wheels. A brake pedal 7 operated by the driver is provided in association with the hydraulic actuator 5, and braking is performed by depressing the brake pedal 7. A detector 8 detects whether the brake pedal 7 is depressed, and it is detected whether the brake pedal 7 is not depressed or not, and the output from the detector 8 is processed. It is input to circuit 2.

FIG. 2 shows an acceleration sensor 1 processed by a processing circuit 2.
12 is a flowchart illustrating an operation for detecting whether or not the device is malfunctioning.

In step n1, it is determined in response to the output of the detector 8 whether or not the brake pedal 7 is not depressed and is not braking. When the brake is not applied, step n2
Next, in response to the output from the wheel speed detection means 3, the maximum value or the center value of the wheel speed is estimated as the vehicle speed, the estimated vehicle speed is obtained in this way, and then, based on this estimated vehicle speed, Then, the difference in estimated vehicle speed per unit time, that is, the estimated vehicle acceleration is determined.

Next, in step n3, the vehicle acceleration detected by the acceleration sensor is compared with the estimated vehicle acceleration, and when the difference between the two exceeds a predetermined value, it is determined that the acceleration sensor has failed and is abnormal. do.

In step n4, when it is determined that the acceleration sensor is abnormal, the process moves to step n5 and performs an anti-skid control operation in the event of a failure of the acceleration sensor, as described in connection with FIG. 40 or FIG. 5, which will be described later. .

The third [2I] shows another embodiment of the present invention and is a flowchart for explaining another operation of the processing circuit 2 executed to detect whether or not the acceleration sensor 1 is out of order. In step m1, if it is determined in response to the output of the detector 8 that the brake pedal 7 is not depressed and braking is not being performed, the process moves to step m2.

In step m2, the estimated vehicle speed V1 is determined by integrating the output from the acceleration sensor. Further, using the output from the wheel speed detection means 3, the estimated vehicle speed V2 is determined by setting the maximum value or an intermediate value of the wheel speed as the vehicle speed.

Therefore, the ratio ΔVS is calculated based on the first equation.

In the next step m3, this ratio Δ■S is set to a predetermined value A
It is determined whether or not it exceeds 1, and if it does, the abnormal time counting counter M1 is incremented by 1.

In step m6, it is determined whether the count value of the counter M1 exceeds a predetermined value A2. When the acceleration sensor is faulty, the ratio Δ■S is the step rn
At step m6, the count value of the counter M1 exceeds the predetermined value A1, and this state continues, so the count value of the counter M1 exceeds the predetermined value A2 at step m6. No. 4121 and No. 5 [Anti-skid according to 2I': rJI In is performed.

When the ratio Δ■S is less than the predetermined value A1 in step m3, it is determined that the acceleration sensor 1 is normal, and the process moves to step m5, where the counter M1 is cleared to zero.

In this way, the vehicle speed is determined based on the output of the acceleration sensor 1, the vehicle speed is determined based on the output from the wheel speed detection hand F13, and the two vehicle speeds obtained in this manner are compared. It is possible to detect whether the acceleration sensor is malfunctioning.

FIG. 4 is a flowchart for explaining the anti-skid control operation when it is determined that the acceleration sensor 1 is out of order and abnormal. The operation shown in FIG. 4 is performed in the processing circuit 2. As shown in FIG. If the acceleration sensor 1 is normal and not broken in step r1, the process moves to step r3, and anti-skid control is performed based on the vehicle speed obtained by integrating the output of the acceleration sensor 1.

When it is determined that the acceleration sensor 1 has failed and is abnormal in step r1, the vehicle body speed calculated and estimated based on the wheel speed from the wheel speed detection means 3 is calculated based on the output from the acceleration sensor 1. In the next step r3, anti-skid control is performed using the same program as the anti-skid control that is executed at 1g when the acceleration sensor 1 is normal.

FIG. 5 is a flowchart showing the operation performed by the processing circuit 2 according to another embodiment of the present invention when the acceleration sensor 1 is abnormal. In the operation shown in FIG. 5, correct anti-skid control is achieved even when the acceleration sensor 1 is out of order. When it is determined in step S1 that the acceleration sensor 1 is normal without any failure, the process moves to step s4, where an undesired skid control program using the estimated vehicle speed obtained by integrating the output of the acceleration sensor 1 is executed. executed.

When it is determined in step s1 that the acceleration sensor 1 has failed and is abnormal, step s
2, the vehicle speed (4c) calculated using the wheel speed detected by the wheel speed detecting means 3 is set as the vehicle body speed used for anti-skid control.Then, moving to step s3, the wheel speed detecting means Anti-skid control is performed using a program different from the anti-skid control in step s4 using the vehicle body speed obtained based on the output from step 3. In this way, when the acceleration sensor 1 is normal, anti-skid control is performed in step S4. In addition, in a state where the acceleration sensor 1 is malfunctioning, an anti-skid control program different from the anti-skid control program in step S4 is executed in step s3.

The aforementioned step s3. Regarding the anti-skid control programs executed in s4, FIGS. 6 to 1
The details will be explained below with reference to FIG.

FIG. 6 is a hydraulic circuit diagram showing a specific configuration of the hydraulic actuator 5. As shown in FIG. 30 is a brake pedal, 31 is a mask cylinder, 32 is a reservoir, 3.3 is a pump, 34
35 is a 3-position electromagnetic switching valve, 37 is a bypass electromagnetic valve, and 38 to 41 are check valves. The hydraulic braking mechanism 6 includes a 3-position electromagnetic switching valve 35 including a foil cylinder.
The output hydraulic pressure of the mask cylinder is supplied to the input port 35a through the vibrator 42, and one output port 35b is connected to the vibrator 4.
3 to the foil cylinder 6, and one other output port 35c is connected to the reservoir 32 through the vibrator 44, and depending on the actuator control signal applied via the line 4 from the processing circuit 2, the following three output ports are connected: It can take a mode.

) Connect the pressure increase mode input port 35a and the output port 35b, and connect the output port 35c.
By closing, the oil pressure of the foil cylinder 6 is increased by the output oil pressure of the mask cylinder 31.

(ii) By not connecting the hold mode input port 35a to any of the output ports 35b and 35c, the oil pressure of the boil cylinder 6 is brought into a hold state.

(iii) 'J! j. The hydraulic pressure of the foil cylinder 6 is reduced by closing the pressure mode input port 35a and connecting the output port 35b and the output port 35c.

On the premise of the structure of the above-mentioned hydraulic actuator 5 shown in FIG. 6, the anti-skid control program executed in step s3 of FIG. 5 when the acceleration sensor 1 fails will be described first.

When performing anti-skid control based on estimated vehicle speed,
In order to accurately estimate the vehicle speed, a control algorithm is developed that, after the wheels are about to lock, reduces the oil pressure sufficiently, restores the wheel speed to a point close to the vehicle speed, and then increases the oil pressure again. (If such control is not performed, the estimated vehicle speed will gradually fall below the vehicle speed, and the wheels may lock before the vehicle comes to a stop, potentially making it impossible to steer the vehicle.)

Therefore, the control map in this case is as shown in FIG. 7, for example. In Fig. 7, the vertical axis is the slip rate λ (λ, λ2), and the slip rate increases as you go down, and the horizontal axis shows acceleration, with the left side decelerating and the right side accelerating around O indicated by the dotted line. It is. Areas Xll to X14 determined by each slip rate and acceleration. X21~X24
．． Symbols shown in X31 to X34 ↓, t, -,
n.

U indicates the control content to be executed when the vehicle is in the state of the region, and has the following meaning.

↓: Pressure reduction is achieved by setting the 3-position electromagnetic switching valve 35 to pressure reduction mode.

↑: Pressure increase, which is achieved by setting the 3-position electromagnetic switching valve 35 to pressure increase mode.

1: Hold, which is achieved by setting the 3-position electromagnetic switching valve 35 to the hold mode.

This is a pulse pressure increase and is achieved by periodically switching the 3-position electromagnetic switching valve 35 between pressure increase mode and hold mode.

(2): Pulse pressure reduction, which is achieved by periodically switching the 3-position electromagnetic switching valve 35 between pressure reduction mode and hold mode.

However, until wheel slip is detected and anti-skid control starts, the brake state is normally R (↑), so there is no movement according to the control map.
The reason why (-) is written together with ↓ means that it is held only at the start of control, and the reason why ('U) is written together with ↓ in area X22 is that the coefficient of friction is small. This means that the pressure is reduced in pulses until it is determined that the road is low, and after it is determined that the road is low, the pressure is reduced. Further, the curve O→■→■→■→■→■→ shown in FIG. 7 shows an example of changes in wheel acceleration and slip rate when traveling on a low μ road.

Various optimal control algorithms based on such estimated vehicle speed have been proposed in the past (for example, I).
CHTECHNISCI(E BERICIITE E
nglisl+5special ediLion
(Febr, 1982) l5SNOOO6-F89
X), any of these algorithms can be used in the present invention.

Acceleration sensor 1 is not malfunctioning and is normal.

Therefore, the anti-skid control program executed in step I84 in FIG. 5 will be described below. When an estimated vehicle speed is calculated based on the output of the acceleration sensor 1 and anti-skid control is performed using this estimated vehicle speed, the control is performed at around the optimum slip ratio without recovering the wheel speed to a point close to the vehicle speed. Because it is possible
Fluctuations in the oil pressure of the wheel cylinder 6 can be reduced, and control with a high average oil pressure can be achieved. An example of a control map that realizes this is shown in Fig. 8. In Fig. 8, the vertical axis is the slip rate α (α1.α,,α,), and the slip rate increases as you go down, and the horizontal axis indicates the acceleration of the wheel, centered on 0, and the left side is the deceleration (ELz, -al
), the right side is acceleration (+A), and regions Y11 to Y15. which are determined by each slip rate and acceleration. Y21-Y25.
Y31~Y35° Symbols shown in Y41~Y45 ↓, ↑.

几 and tr indicate the control content to be executed when the vehicle is in the state of the region, and their meanings are the same as described above.

° Also, the curve →■→■→■→■→... shown in Figure 8 shows an example of changes in wheel acceleration and slip rate when driving on a low μ road, and Figure 9 shows the wheel acceleration at that time. , shows temporal changes in wheel speed, control status, and wheel cylinder oil pressure. That is, when the foot brake 7 is stepped on, the area Y13. At Y12, anti-skid control has not started, so pressure increase control (normal braking) is performed, and when entering area Y22, anti-skid control is started and pulse pressure is reduced.
Area Y21. Y31. Y41. Y42. Y43. Y44
The pressure is reduced in the region Y34, the pressure is increased in pulses in the region Y33, the pressure is reduced in pulses in the region Y33, and thereafter the pressure is reduced in the region Y34. Y33
This shows that pulse pressure reduction and pulse pressure increase are repeated by going back and forth.

The processing circuit 2 shown in FIG. 1 controls the hydraulic actuator 5 in accordance with the control maps shown in FIGS. 7 and 8, and various methods can be adopted to achieve this, examples of which are as follows. is shown in FIG. 10. The control flow in FIG. 10 corresponds to the control map in FIG. 8, and the wheel acceleration (V w
) is located in one of the five sections shown in FIG. 8, and depending on the result, the value of the last digit of the number in areas Yll to Y45 is stored in the upper byte RH of the internal register of the processing circuit 2. It is determined in which of the four categories shown in FIG. 8 the slip ratio α calculated from the contents obtained from the storage processes slO to s18, the wheel acceleration and the vehicle body acceleration, and the internal register is stored according to the result. Area Y11 in the lower byte RL of
．． Process s19 to store the value of the second last digit of the number Y45
s25, and step s26 in which the control contents corresponding to the values stored in the upper byte RH and lower byte RL of the internal register are read from the control map in FIG. 8 and the control is executed.

Effects of the Invention As described above, according to the present invention, it is possible to detect whether or not the acceleration sensor fixed to the body of the automobile is malfunctioning, and to detect whether or not the acceleration sensor is malfunctioning. This makes it possible to perform anti-skid control correctly even when the vehicle is closed.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of the present invention, FIG. 2 is a flowchart for explaining the operation performed by the processing circuit 2 to detect whether or not the acceleration sensor 1 is malfunctioning, and FIG. FIG. 4 is a flowchart for explaining other operations performed by the processing circuit 2 to detect whether or not the acceleration sensor 1 is malfunctioning; FIG. 4 is a flowchart for explaining the anti-skid control operation performed by the processing circuit 2; FIG. 5 is a flowchart showing the operation performed by the processing circuit 2 of another embodiment of the present invention when the acceleration sensor 1 is abnormal, FIG. 6 is a hydraulic circuit diagram showing the specific configuration of the hydraulic actuator 5, and FIG. Figure 8 shows the control map of the anti-skid control program executed in step s3 of Figure 5 when acceleration sensor 1 is out of order, and Figure 8 [] shows the control map of Figure 5 when acceleration sensor 1 is normal. A diagram showing the control map of the anti-skid system (1 progerano) executed in step s4, FIG. 9 is a diagram explaining the operation during control using the control map shown in FIG. 8, and FIG. 9 is a flowchart of a control content determination process performed by the processing circuit 2 when the operation shown in FIG.・Hydraulic actuator, 6...
・Hydraulic braking mechanism, 7...Brake pedal, 8...Non-braking detector Agent Patent attorney Number of strokes Keiichibe Part 1 Figure 2 Figure M3 Figure Deadline processing Figure 4 Figure 5rj: I Figure 6! Figure 7 'A desecration ← 0 → Caliao stage Figure 8 - OX -010+A = prison cicadas imaginary A Figure 9

Claims (1)

[Scope of Claims] (1) An acceleration sensor fixed to the body of an automobile, a means for detecting that braking is not performed, a means for detecting wheel speed, and a means for detecting wheel speed in response to the output of the wheel speed detecting means. , an estimation calculating means for calculating an estimated vehicle speed and calculating an estimated vehicle acceleration based on the estimated vehicle speed; and an estimation calculating means for determining an estimated vehicle body acceleration based on the estimated vehicle speed; What is claimed is: 1. A failure detection device for an acceleration sensor, comprising means for comparing a vehicle body acceleration detected by the vehicle with an estimated vehicle body acceleration obtained by an estimation calculating means. (2) An acceleration sensor fixed to the vehicle body, a means for detecting that braking is not being performed, a means for detecting wheel speed, and a means for detecting wheel speed in response to an output from the acceleration sensor. a first vehicle speed calculation means for calculating an estimated vehicle speed by integrating; a second vehicle speed calculation means for calculating and estimating the vehicle speed in response to the output from the wheel speed detection means; and a non-braking detection means. and means for comparing respective outputs from the first and second vehicle body speed calculation means when it is detected that the vehicle is not braking. (3) an acceleration sensor fixed to the vehicle body, a device for detecting a failure of the acceleration sensor, a means for detecting wheel speed, and a device that responds to the output of the acceleration sensor failure detection device when the acceleration sensor is normal; Anti-skid control is performed based on the vehicle speed obtained by calculating the output of the acceleration sensor, and when the acceleration sensor is malfunctioning, the vehicle speed obtained from the output of the wheel speed detection means is calculated by calculating the output of the acceleration sensor. 1. An anti-skid control device comprising means for performing anti-skid control using the same program as an anti-skid control that is executed when an acceleration sensor is normal based on the assumption that the vehicle speed is a normal vehicle speed. (4) An acceleration sensor fixed to the vehicle body, a device for detecting failure of the acceleration sensor, a means for detecting wheel speed, and a means for detecting wheel speed, which detects acceleration when the acceleration sensor is normal. Anti-skid control is performed based on the vehicle speed obtained by calculating the output of the sensor, and when the acceleration sensor is malfunctioning, the output of the wheel speed detection means is used to perform anti-skid control when the acceleration sensor is normal. 1. An anti-skid control device comprising means for performing anti-skid control using a program different from anti-skid control.