JPH11287820A - Apparatus for judging output state of acceleration sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an apparatus for judging an output state of an acceleration sensor that can surely judge whether or not an output signal of the acceleration sensor is oscillating SOLUTION: This apparatus has a peak value detection means PD for detecting a continuous peak value of an output signal of an acceleration sensor LS and a bottom value detection means BD for detecting a continuous bottom value of the output signal. A deviation operation means DF operates a deviation from a first bottom value detected continuously with a first peak value, and a passed time detection means TD detects a time passed after the first peak value is detected before the first bottom value is detected. Moreover, a first comparison means C1 compares the deviation with a reference value and a second comparison means C2 compares the passed time with a reference time. In accordance with the comparison results whereby the deviation is judged to be not smaller than the reference value and the passed time is judged to be not larger than the reference time, an output state judgment means OP judges that the output signal of the acceleration sensor LS is oscillating.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an output state judging device for an acceleration sensor, and more particularly to an output state judging device for an acceleration sensor capable of judging whether or not an output signal of a linear longitudinal acceleration sensor is in a vibration state. .

[0002]

2. Description of the Related Art An anti-skid control device is known as a device for preventing a wheel from being locked and slipping during braking of a vehicle, but an acceleration sensor is used for estimating a vehicle speed required for the control. ing. For example, Japanese Patent Laying-Open No. 2-28045 proposes a method of estimating a vehicle speed using an analog acceleration sensor having a linear characteristic. According to the publication, when the vehicle is on an uphill or downhill, the gravitational acceleration corresponding to the slope of the uphill or downhill is already acting on the acceleration sensor. In view of the fact that the output of the vehicle becomes zero, it has been proposed to estimate the vehicle speed based on a value obtained by adding a first set value corresponding to an inclination of an uphill road to the absolute value of the output of the acceleration sensor.

[0003]

The above-mentioned JP-A-2-28
In the vehicle body speed estimation method disclosed in Japanese Patent No. 045, an acceleration sensor is used. Although measures are taken to prevent the vehicle from inclining, when the vehicle or wheels vibrate, the output of the acceleration sensor also vibrates. Estimating speed is not easy. It is general to take measures against such vibrations so as to output through a filter. However, it is difficult to obtain high-precision output using only the filter, and a delay due to the filter occurs.

The road surface on which a vehicle travels is generally classified into a good road and a bad road, and the bad road includes an unpaved road, a cobblestone road, a snowy road, and the like. Of these, unpaved roads include gravel roads and dirt roads. A dirt road is an earth surface, and a gravel road includes sand. With respect to such various road surfaces, means for determining a rough road such as a good road or a bad road have already been proposed and are in practical use, but are provided on unpaved roads including gravel roads and dirt roads. There is no known road decision. In an anti-skid control device mounted on a commercially available vehicle, a lock state of each wheel during braking is controlled according to a road surface condition (good road or bad road). It is not determined whether the vehicle is traveling on a dirt road.

Naturally, the same processing is not performed on gravel roads and dirt roads as unpaved roads. For example, brake fluid pressure control on gravel roads and brake fluid pressure on dirt roads during anti-skid control are performed. It is desirable to perform the control separately, but it is very difficult to detect the gravel road and the dirt road.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an acceleration sensor output state determination device capable of reliably determining whether an output signal of an acceleration sensor is in a vibration state.

Further, the present invention provides an acceleration sensor capable of reliably determining whether a vehicle is traveling on a gravel road or a dirt road even if the output signal of the acceleration sensor is in a vibrating state. Another object is to provide an output state determination device.

[0008]

According to the present invention, there is provided an acceleration sensor for detecting acceleration relative to a vehicle and outputting a signal proportional to the acceleration. An output state determination device for determining a state of an output signal of the output signal; a peak value detection unit for detecting a continuous peak value of the output signal; a bottom value detection unit for detecting a continuous bottom value of the output signal; Deviation calculating means for calculating a deviation between a first peak value detected by the value detecting means and a first bottom value detected by the bottom value detecting means continuously from the first peak value; The elapsed time detecting means for detecting an elapsed time from when the means detects the first peak value to when the bottom value detecting means detects the first bottom value, and the deviation calculating means calculates First comparing means for comparing the deviation with a reference value, second comparing means for comparing the elapsed time detected by the elapsed time detecting means with a reference time, and comparison between the first and second comparing means. Output state determining means for determining the state of the output signal according to the result. In the peak value detecting means, for example, when the output signal of the acceleration sensor indicates a deceleration is defined as positive, the value obtained when the differential value is switched from a positive value to a negative value is determined as the peak value. Can be set as Similarly, in the bottom value detecting means, when the case where the output signal of the acceleration sensor indicates deceleration is defined as positive, the value when the differential value is switched from a negative value to a positive value is determined as the bottom value. Can be set as

The output state judging means changes the output signal of the acceleration sensor to a vibration state when it is determined that the deviation is equal to or more than a reference value and the elapsed time is equal to or less than a reference time. It may be configured to determine that there is.

According to another aspect of the present invention, an output state determination for detecting an acceleration signal in a longitudinal direction with respect to the vehicle and for determining a state of an output signal of an acceleration sensor for outputting a signal linearly proportional to the acceleration. In the apparatus, a peak value detecting means for detecting a continuous peak value of the output signal, and a fluctuation between a first peak value and a second peak value continuously detected by the peak value detecting means are detected. The apparatus may further include a fluctuation detecting unit, and an output state determining unit that determines a state of the output signal based on a fluctuation between the first and second peak values detected by the fluctuation detecting unit.

Further, the output state judging means according to claim 3 is configured to decelerate the output signal during the period from the first peak value to the second peak value. When the fluctuation detecting means detects that the vehicle has increased beyond a predetermined upper limit, it is determined that the vehicle is traveling on a gravel road, and during the period from the first peak value to the second peak value, When the fluctuation detecting means detects that the deceleration of the output signal is within a predetermined range equal to or lower than a predetermined upper limit, the vehicle may be determined to be traveling on a dirt road.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an overall configuration of an output state determination device for an acceleration sensor according to an embodiment, which detects longitudinal acceleration of a vehicle (not shown) and outputs a signal linearly proportional to the acceleration. This is to determine the state of the output signal of the acceleration sensor LS. The acceleration sensor LS is connected to a peak value detecting means PD for detecting a continuous peak value of the output signal and a bottom value detecting means BD for detecting a continuous bottom value of the output signal. The deviation calculating means DF calculates the deviation between the first peak value detected by the peak value detecting means PD and the first bottom value detected by the bottom value detecting means BD continuously to the first peak value. The elapsed time detecting means TD detects the elapsed time from when the peak value detecting means PD detects the first peak value to when the bottom value detecting means BD detects the first bottom value. Further, the first comparator C1 compares the deviation calculated by the deviation calculator DF with a reference value, and the second comparator C2 compares the elapsed time detected by the elapsed time detector TD with the reference time. . Then, the output state determination means OP is configured to determine the state of the output signal according to the comparison result of the first and second comparison means C1 and C2. For example, when it is determined that the deviation is equal to or greater than the reference value and the elapsed time is equal to or less than the reference time, it is determined that the output signal of the acceleration sensor LS is in a vibration state.

Further, as shown by a broken line in FIG. 1, a fluctuation detecting means V for detecting a fluctuation between the first peak value and the second peak value continuously detected by the peak value detecting means PD.
If D is provided, the output state determination unit OP determines the state of the output signal based on the fluctuation between the first and second peak values detected by the fluctuation detection unit VD. For example, when the fluctuation detecting means VD detects that the deceleration of the output signal has increased beyond the predetermined upper limit during the period from the first peak value to the second peak value, the vehicle moves along the gravel road. It is determined that the vehicle is traveling, and the fluctuation detection means VD has detected that the deceleration of the output signal is within a predetermined range equal to or less than a predetermined upper limit during a period from the first peak value to the second peak value. Sometimes, it is determined that the vehicle is traveling on a dirt road.

FIG. 2 shows an anti-skid control device including the acceleration sensor and the output state determining device according to the above-described embodiment. The anti-skid control device includes a master cylinder 2a and a booster 2b as hydraulic pressure generating means, and these are brakes. It is driven by the pedal 3. Each wheel FR, FL, RR, R
Wheel cylinders 51 to 54 are mounted on L. The wheel FR indicates the front right wheel as viewed from the driver's seat, the wheel FL indicates the front left wheel, the wheel RR indicates the rear right wheel, and the wheel RL indicates the rear left wheel. As is apparent from FIG. Although piping is configured, so-called front and rear piping may be used.

An anti-skid control (A) is provided between the master cylinder 2a and the wheel cylinders 51 to 54.
BS) actuator 30 is interposed. The actuator 30 is configured as shown by a two-dot chain line in FIG. 2, and a normally open solenoid valve 31 is connected to a hydraulic path connecting one output port of the master cylinder 2a and each of the wheel cylinders 51 and 54. , 37 are interposed, and the discharge side of the hydraulic pump 21 is connected between these and the master cylinder 2a. Similarly, normally open solenoid valves 33 and 35 are interposed in a hydraulic path connecting the other output port of the master cylinder 2a and each of the wheel cylinders 52 and 53, and a hydraulic fluid is provided between these and the master cylinder 2a. The discharge side of the pressure pump 22 is connected. The hydraulic pumps 21 and 22 are driven by the electric motor 20, and at the time of their operation, the brake fluid whose pressure has been raised to a predetermined pressure is supplied to each of the above hydraulic paths.

The wheel cylinders 51, 54 are further connected to normally closed solenoid valves 32, 38, and their downstream sides are connected to the reservoir 23 and to the suction side of the hydraulic pump 21. The wheel cylinders 52, 53 are also connected to normally closed solenoid valves 34, 36, and their downstream sides are connected to the reservoir 24 and the hydraulic pump 2
2 is connected to the suction side. Each of the reservoirs 23 and 24 has a piston and a spring, and the solenoid valves 32 and 3
The brake fluid of each wheel cylinder discharged through 4, 36, 38 is stored.

The solenoid valves 31 to 38 are two-port two-position solenoid switching valves, each of which is shown in FIG.
, Each of the wheel cylinders 51 to 54 communicates with the master cylinder 2a. When the solenoid coil is energized, it is in the second position, and the wheel cylinders 51 to 54 are cut off from the master cylinder 2a and communicate with the reservoir 23 or 24. In FIG. 2, PV is a proportioning valve, DP is a damper, CV
Indicates a check valve, OR indicates an orifice, and FT indicates a filter. In FIG. The check valve CV permits recirculation from the wheel cylinders 51 to 54 and the reservoirs 23 and 24 to the master cylinder 2a, and shuts off the flow in the reverse direction.

The brake fluid pressure in the wheel cylinders 51 to 54 can be increased, reduced or maintained by controlling the energization and non-energization of the solenoid coils of the solenoid valves 31 to 38. That is, the solenoid valve 3
When the solenoid coils 1 to 38 are not energized, the brake fluid pressure is supplied from the master cylinder 2a and the hydraulic pump 21 or 22 to the wheel cylinders 51 to 54 to increase the pressure, and when energized, the wheel cylinders 51 to 54 are moved to the reservoir 23 or 24 side. Reduce the pressure through communication. When the solenoid coils of the solenoid valves 31, 33, 35, and 37 are energized and the solenoid coils of the other solenoid valves are deenergized, the brake fluid pressure in the wheel cylinders 51 to 54 is maintained. Accordingly, by adjusting the time interval between energization and non-energization of the solenoid coil, pulse pressure increase (step pressure increase) can be performed as described later, and control can be performed so as to increase the pressure gradually. Can be controlled to reduce the pressure.

The solenoid valves 31 to 38 are connected to the electronic control unit 1
0, energizing each solenoid coil,
De-energization is controlled. The electric motor 20 is also the electronic control unit 1
0, which controls the drive. Wheel speed sensors 41 to 4 are attached to the wheels FR, RL, RR, FL.
4 are connected to the electronic control unit 10, and the rotation speed of each wheel, that is, a wheel speed signal is input to the electronic control unit 10. Further, the vehicle is equipped with a linear longitudinal acceleration sensor 1 (hereinafter, referred to as a linear G sensor 1) as an acceleration sensor of the present invention, and an output signal thereof is input to the electronic control unit 10. The electronic control unit 10 is further connected with a brake switch 4 and the like which are turned on when the brake pedal 3 is depressed.

As shown schematically in FIG. 2, the linear G sensor 1 converts the forward / backward movement of the weight in accordance with the acceleration / deceleration of the vehicle into an electric signal, and responds to the acceleration (including deceleration) of the vehicle. It outputs a signal that is linearly proportional and is already on the market, so a detailed description is omitted. The electronic control unit 10 is constituted by a general microcomputer, and although not shown, a central processing unit (CPU), a memory (ROM, RAM), a timer, It consists of an input / output interface.

In this embodiment constructed as described above, a series of processing for anti-skid control is performed by the electronic control unit 10 to control the operation of the actuator 30. Hereinafter, the operation will be described with reference to the flowchart of FIG. Will be explained. When an ignition switch (not shown) is closed, initialization is first performed in step 101 of FIG. 2, and various calculation values are cleared. In step 102, the wheel speed (represented by Vw) of each wheel is calculated based on the output signals from the wheel speed sensors 41 to 44. In step 103, the wheel speed Vw is differentiated to obtain the wheel acceleration D.
Vw is required. Then, in step 104, the estimated vehicle speed Vso is calculated based on the wheel speed Vw of each wheel. The estimated vehicle speed Vso is, for example, MED (α
_DN t, Vw, α _UP t). Here, MED represents a function for obtaining an intermediate value, α _UP is a value on an upper limit side (a side larger than the wheel speed Vw) of the vehicle acceleration (including deceleration) α, and α _DN is a lower limit of the acceleration α. Side (a side smaller than the wheel speed Vw), and t is time. The vehicle speed can be directly detected by, for example, a ground sensor.

Then, the program proceeds to a step 105, wherein the actual slip ratio of each wheel to be subjected to the anti-skid control (typically, S
is calculated (Sa = (Vso−Vw) / Vs)
o). Subsequently, the routine proceeds to step 106, where a target slip ratio is set for each wheel. Next, at step 107, the output Gx of the linear G sensor 1 is read. Step 10
At 8, a bad road determination is made, but the bad road mentioned here is not limited to an unpaved road, but includes a cobblestone road, a snowy road, and the like. Then, the process proceeds to a step 109, wherein the output state of the linear G sensor 1 is determined, which will be described later with reference to FIG.

Next, at step 110, it is determined whether or not the anti-skid control is being performed. If it is not under the anti-skid control, it is determined at step 113 whether or not the anti-skid control has been started. If the anti-skid control has already been performed, the process proceeds to step 111, where it is determined whether the traveling road surface of the vehicle is a gravel road or a dirt road. This will be described later with reference to FIG. If it is determined in step 111 that the road is a gravel road or a dirt road, the anti-skid control condition is switched to that for a gravel road or a dirt road in step 112. Otherwise, the process proceeds to step 114.

On the other hand, in step 113, the locked state of each wheel is determined based on, for example, the wheel speed Vw and the wheel acceleration DVw, and it is determined whether or not the start condition of the anti-skid control is satisfied. If the start condition is satisfied, the process proceeds to step 111, and if not, the process returns to step 102.

In step 114, the control mode is set to one of the pressure reduction mode, the pulse pressure reduction mode, the pulse pressure increase mode, and the holding mode in accordance with the locked state of each wheel. Then, a hydraulic pressure control signal corresponding to each control mode is output. Thus, based on each control mode, energization and non-energization of each of the solenoid coils of the solenoid valves 31 to 38 are controlled as described above, and the brake fluid pressure (wheel cylinder fluid pressure) in the wheel cylinders 51 to 54 is increased. Increase, decrease or hold.

The determination of the output state of the linear G sensor 1 executed in step 109 is performed according to the flowchart shown in FIG. First, in step 201, a filtering process is performed on the output value Gx (the deceleration side is represented by a positive value) of the linear G sensor 1, and the filtered value Gf is provided for subsequent control. Next, step 202
, The filtered value Gf of the output of the linear G sensor 1
Deceleration peak value Gp (hereinafter simply referred to as peak value Gp
Is performed. Specifically, a value when the differential value of the filtered value Gf is switched from a positive value to a negative value is detected as the peak value Gp. Subsequently, in step 203, it is determined whether or not the peak value Gp has been detected in the current cycle. If the peak value Gp is detected in the current cycle, the process proceeds to step 204, where the timer value Tp is cleared. If the peak value Gp has not been detected in this cycle, the process proceeds to step 205, where the timer value Tp at that time is counted up.

Then, the process proceeds to a step 206, wherein the linear G
Detection processing of the deceleration bottom value Gb (hereinafter simply referred to as the bottom value Gb; the peak value on the acceleration side) with respect to the filter processing value Gf of the output of the sensor 1 is performed. Specifically, a value when the differential value of the filtered value Gf is switched from a negative value to a positive value is detected as the bottom value Gb, and in step 207, the timer of the timer when the bottom value Gb is detected is detected. The value Tp is stored as MTp. This value MTp corresponds to the elapsed time from when the peak value Gp is detected to when the bottom value Gb is detected.

Then, the routine proceeds to step 208, where the absolute value of the difference between the peak value Gp and the bottom value Gb (| Gp-Gb |)
Is calculated, and the absolute value of this difference (| Gp-Gb |) is the first
Is compared with the reference value G1. The absolute value of the difference (| Gp-Gb
If |) is equal to or greater than the first reference value G1, the process proceeds to step 209, and the elapsed time (the value of MTp) from the peak value Gp to the bottom value Gb is compared with the reference time T1. If the elapsed time (the value of MTp) is equal to or less than the reference time T1, the process proceeds to step 210, where it is determined that the output of the linear G sensor 1 is vibrating, and the sensor vibration flag Fv is set (1). An example of the above relationship is shown in FIG.

On the other hand, when the absolute value (| Gp-Gb |) of the difference between the peak value Gp and the bottom value Gb is smaller than the first reference value G1, the output of the linear G sensor 1 is not vibrating, Non-vibration is set, and step 208 to step 2
Proceeds to 11, and the sensor vibration flag Fv is reset (0)
Is done. Further, even when the absolute value of the difference (| Gp-Gb |) is equal to or greater than the first reference value G1, the elapsed time (the value of MTp) from the peak value Gp to the bottom value Gb is longer than the reference time T1. If so, since the change is gradual, the process proceeds from step 209 to step 211, and the sensor vibration flag Fv is reset (0).

FIG. 5 shows a judgment process of a gravel road or a dirt road executed in step 111 of FIG. 3. First, in step 301, whether or not the vehicle is traveling on a rough road is determined based on the result of the judgment in step 108. If not, the process returns to the main routine if it is not a bad road. If it is determined in step 301 that the road is bad, the process proceeds to step 302, where the four-wheel average slip ratio Sea is calculated based on the average wheel speeds Vea of all the wheels (Sea = (Vso-Vea) / Vso). This is equivalent to μ-S when the slip ratio is the average slip ratio of all wheels.
(Friction coefficient-slip ratio) curve and G-S (vehicle deceleration-
This is because the curve (slip ratio) accurately corresponds to the case. When urgency is important, the minimum value MIN (Vw) of the wheel speeds of all the wheels of the vehicle is obtained, and the minimum value MIN (Vw) is calculated based on this and the estimated vehicle speed Vso. The wheel maximum slip ratio may be determined and used instead of the four-wheel average slip ratio Sea.

Further, in step 303, the slip ratio Sea
Is filtered, and the filtered value Sef is used for subsequent control. Then, proceed to step 304,
It is determined whether or not the filter processing value Sef of the four-wheel average slip ratio Sea has been changed from a value lower than the first reference slip ratio S1 (for example, 10%) to a value higher than the first reference slip ratio S1 (for example, 10%). If not, the process returns to the main routine. In step 305, the filtered value Gf of the output of the linear G sensor 1 when the filtered value Sef of the four-wheel average slip rate Sea exceeds the first reference slip rate S1 is set to the deceleration Gc.

Next, the routine proceeds to step 306, where it is determined whether or not the slip ratio peak Sp has been detected. As the slip ratio peak Sp, the slip ratio when the differential value of the filtered value Sef of the four-wheel average slip ratio Sea is switched from a negative value to a positive value is used. Slip rate peak Sp
Is detected, the process proceeds to step 307, where the linear G
The output state of the sensor 1 is determined. That is, if the sensor vibration flag Fv has been reset based on the determination result of the output state of the linear G sensor 1 in step 109 in FIG. 3, the process proceeds from step 307 to step 308 and thereafter.
If the sensor vibration flag Fv is set, the process proceeds to step 313. If the slip ratio peak Sp is not detected in step 306, the process returns to the main routine.

In step 308, the filter processing value Gf of the output of the linear G sensor 1 at that time is
is set to d. Thereafter, the process proceeds to step 309, where the difference (Gd-Gc) between the deceleration Gd and the deceleration Gc is calculated, and the calculation result is compared with the second reference value G2. As a result, if the difference (Gd-Gc) is larger than the second reference value G2, the process proceeds to step 310; otherwise, the process returns to the main routine. In other words, the deceleration Gd at the time when the slip ratio peak Sp is detected is larger than the four-wheel average slip ratio Sea.
If it is determined that the filter processing value Sef is greater than or equal to the second reference value G2 from the deceleration Gc when the filter processing value Sef exceeds the first reference slip ratio S1, unpaved one of the gravel road and the dirt road The road is determined, and the routine proceeds to step 310, where the difference (Gd-Gc) between the deceleration Gd and the deceleration Gc is compared with the third reference value G3. As a result, if the difference (Gd−Gc) is equal to or less than the third reference value G3, the process proceeds to step 311;
It is determined to be a dirt road. On the other hand, the difference (Gd-Gc)
Is larger than the third reference value G3, the routine proceeds to step 312, where it is determined that the road is a gravel road. The situation during this time is shown in FIG.

On the other hand, if it is determined in step 307 that the linear G sensor 1 is vibrating, then in step 313, the difference (Gp1-Gp0) between the current deceleration peak value Gp1 and the previous deceleration peak value Gp0 is calculated. The calculation result is compared with a fourth reference value G4 (when the deceleration is set to a positive value, G4 is set to a negative value). As a result, the difference (Gp1
-Gp0) is greater than the fourth reference value G4, step 3
Go to 14, otherwise return to the main routine. In step 314, the difference (Gp1-Gp0) is further changed to the fifth.
(G4 <G5, G5 is a positive value)
The filter processing value Gf of the output of the linear G sensor 1 is increasing in the deceleration direction if it is larger than this. Therefore, it is determined in step 312 that the road is a gravel road.
Therefore, if the difference (Gp1-Gp0) is equal to or smaller than the fifth reference value G5 (but larger than the fourth reference value G4), the filtered value Gf is within a substantially constant range (near 0), It is determined to be a dirt road. In step 313, the difference (Gp1-G
If (p0) is determined to be equal to or smaller than the fourth reference value G4, it means that the filter processing value Gf has decreased, and the process returns to the main routine of FIG.

FIG. 6 shows the control switching of the gravel road / dirt road executed in step 112 of FIG. 3. If it is determined in step 111 that the road is a gravel road, the flow advances from step 401 to step 402 to process the gravel road. Is performed. If it is determined in step 115 that the road is a dirt road, step 40
From step 1,403, the process proceeds to step 404, where dirt road processing is performed. If it is neither a gravel road nor a dirt road, the process returns to the main routine. The processing for the gravel road and the dirt road adjusts the actuator 30 to the pressure increasing side in comparison with the brake fluid pressure control in the anti-skid control when traveling on a pavement road. Specifically, for example, the following series of Processing is performed. That is, (1) the target slip rate is set to be large, and the pressure increase amount is increased and the pressure decrease amount is decreased as compared with the brake fluid pressure control when traveling on a pavement road.
(2) The holding mode performed immediately after the end of the normal pressure reduction mode is prohibited. (3) The upper limit value (α _UP ) of the acceleration α used for the calculation of the estimated vehicle speed Vso is set small. Then, (4) the reference vehicle speed for control end determination is set to high speed.

Further, the processing for the gravel road in step 402 and the processing for the dirt road in step 404 are set under different conditions. Specifically, the correction amount on the pressure increasing side in the processing for the dirt road is set to be smaller than the correction amount on the pressure increasing side in the processing for the gravel road. For example, the increase and decrease rates with respect to the pressure increase amount and the pressure decrease amount when the target slip ratio is set are set smaller in the dirt road process than in the gravel road process, respectively. Further, the ratio of setting the upper limit value (α _UP ) of the acceleration α used for the calculation of the estimated vehicle speed Vso to be small is set to be larger in the process for the dirt road than in the process for the gravel road.

It should be noted that the output state determination device of the acceleration sensor of the present invention is not limited to the anti-skid control device of the above-described embodiment, but also includes the traction control, the vehicle stability control, and the longitudinal braking force distribution control. It can be applied to a control device. In this case, for example, when applied to traction control, the determination target is reversed on the deceleration side and the acceleration side from the above-described embodiment, and the acceleration peak value and the acceleration bottom value are used during traction control. However, processing can be performed in the same manner as in the above-described embodiment.

[0038]

The present invention has the following effects because it is configured as described above. That is, in the output state determination device of the acceleration sensor according to the first and second aspects, the first peak value of the output signal of the acceleration sensor detected by the peak value detection means is continuous with the first peak value. Calculating the deviation from the first bottom value detected by the bottom value detecting means, and detecting the first bottom value from the time when the peak value detecting means detects the first peak value. The elapsed time until the elapsed time is detected, the deviation calculated by the deviation calculating means is compared with a reference value, the elapsed time detected by the elapsed time detecting means is compared with the reference time, and the comparison result of the first and second comparing means is obtained. Is configured to determine the state of the output signal in accordance with the above, it is possible to reliably determine whether or not the output signal of the acceleration sensor is in a vibration state.

According to the third aspect of the present invention, in addition to the above, the output state determination device for the acceleration sensor further comprises:
Fluctuation detecting means for detecting a fluctuation from the first peak value to the second peak value continuously detected by the peak value detecting means is provided, and the first and second peaks detected by the fluctuation detecting means are provided. Based on the variation between the values, the output state determination means is configured to determine the state of the output signal,
The gravel road and the dirt road can be reliably distinguished with a simple configuration, and accordingly, various controls can be appropriately performed according to the gravel road or the dirt road.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating an overall configuration of an output state determination device for an acceleration sensor according to an embodiment of the present invention.

FIG. 2 is a block diagram illustrating an acceleration sensor and an anti-skid control device including the output state determination device according to the embodiment of the present invention.

FIG. 3 is a flowchart illustrating a process for anti-skid control according to an embodiment of the present invention.

FIG. 4 is a flowchart illustrating a process of determining a sensor output state according to an embodiment of the present invention.

FIG. 5 is a flowchart illustrating a gravel road / dirt road determination process according to an embodiment of the present invention.

FIG. 6 is a flowchart showing control switching between a gravel road and a dirt road in one embodiment of the present invention.

FIG. 7 is a graph showing an example of an output state of the acceleration sensor according to the embodiment of the present invention.

FIG. 8 is a graph showing an example of a relationship between a slip ratio and a deceleration on a gravel road and a dirt road.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Linear longitudinal acceleration sensor 2a Master cylinder 2b Booster 3 Brake pedal 10 Electronic control unit 20 Electric motor 21,22 Hydraulic pump 23,24 Reservoir 30 Actuator 31-36 Solenoid valve 41-44 Wheel speed sensor 51-54 Wheel cylinder FR, FL, RR, RL wheels

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hiraku Kato 2-1-1 Asahi-cho, Kariya-shi, Aichi Aisin Seiki Co., Ltd. (72) Inventor Shinji Tsugawa 2-1-1 Asahi-cho, Kariya-shi, Aichi (72) Inventor Koichi Kondo 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation

Claims (4)

[Claims] 1. An output state determination device for detecting an acceleration of a vehicle and outputting a signal proportional to the acceleration to determine a state of an output signal of an acceleration sensor, wherein a continuous peak value of the output signal is detected. A peak value detecting means, a bottom value detecting means for detecting a continuous bottom value of the output signal, a first peak value detected by the peak value detecting means, and the bottom value continuous with the first peak value. Deviation calculating means for calculating a deviation from the first bottom value detected by the detecting means; and the bottom value detecting means detecting the first peak value from the time when the peak value detecting means detects the first peak value.
Elapsed time detecting means for detecting an elapsed time until the bottom value is detected, first comparing means for comparing the deviation calculated by the deviation calculating means with a reference value, and detecting the elapsed time by the elapsed time detecting means. A second comparison unit that compares the elapsed time with a reference time; and an output state determination unit that determines a state of the output signal according to a comparison result of the first and second comparison units. An output state determination device for an acceleration sensor. 2. The output state determination means is configured to determine that the output signal of the acceleration sensor is in a vibration state when it is determined that the deviation is equal to or greater than a reference value and the elapsed time is equal to or less than a reference time. 2. The output state judging device for an acceleration sensor according to claim 1, wherein: 3. An output state judging device which detects an acceleration signal in a front-rear direction with respect to a vehicle and outputs a signal linearly proportional to the acceleration to determine a state of an output signal of the acceleration sensor. Peak value detecting means for detecting a peak value, fluctuation detecting means for detecting fluctuation between a first peak value and a second peak value continuously detected by the peak value detecting means, and fluctuation detecting means Output state determination means for determining a state of the output signal based on a change between the first and second peak values detected by the output state determination apparatus. 4. The fluctuation detecting section detects that the deceleration of the output signal has increased beyond a predetermined upper limit during a period from the first peak value to the second peak value. When the means detects, it is determined that the vehicle is traveling on a gravel road, and the deceleration of the output signal is within a predetermined range within a predetermined upper limit value from the first peak value to the second peak value. 4. The output state determination device for an acceleration sensor according to claim 3, wherein when the fluctuation detecting means detects that the vehicle is in the vehicle, the vehicle is determined to be traveling on a dirt road.