JPH0740040B2 - Lateral acceleration sensor abnormality detection device - Google Patents

Description

The present invention is used as a sensor for providing lateral acceleration information in a control system such as a front / rear wheel driving force distribution control device, an active suspension control device, or a four-wheel steering control device. The present invention relates to a lateral acceleration sensor abnormality detection device.

(Prior Art) Conventionally, as a lateral acceleration output value correction device applied to an active suspension control device, for example, JP-A-63-
The device described in Japanese Patent No. 134319 is known.

According to this conventional source, when a straight running state in which no lateral acceleration occurs in the vehicle and lateral acceleration does not occur is determined, the acceleration detection value in the acceleration non-occurrence state is used as a correction reference value, and this correction reference value is set as the correction reference value. There is shown a device in which the lateral acceleration detection value from the acceleration sensor is offset-corrected based on this, and the lateral acceleration correction value obtained by this correction processing is used as control information for active suspension control.

(Problems to be Solved by the Invention) However, such a conventional lateral acceleration output value correction device is a device on the assumption that the lateral acceleration sensor is normal. This is an effective device when the detected value is output with an offset error, but the lateral acceleration detected value from the sensor always outputs a constant value, and the detected value that fluctuates regardless of the vehicle lateral acceleration is detected. When the so-called lateral acceleration sensor is abnormal such as outputting, the control system using the lateral acceleration detection value as control information is significantly affected.

For example, in the front / rear wheel driving force distribution control device, since the control gain is determined by the lateral acceleration detection value, the occurrence of driving wheel slip, tight corner braking, etc. is allowed due to insufficient or excessive clutch engagement force.

Therefore, as a device for detecting abnormality of the lateral acceleration sensor,
A device in which two or more lateral acceleration sensors are provided and an abnormality is detected by comparing detection values from these sensors is conceivable, but in this case, the cost becomes high.

The present invention has been made in view of the above-mentioned problems, and when the abnormality of the lateral acceleration sensor applied to various vehicle control systems is accurately detected by a cost-effective device and the abnormality is left unattended. The challenge is to minimize the impact on the control system that occurs in the system.

(Means for Solving the Problem) In the lateral acceleration sensor abnormality detection device of the present invention in order to solve the above-mentioned problems, the lateral acceleration estimated value obtained by calculation based on the left and right steering wheel rotation speeds is used for abnormality determination. As a base, a device for detecting an abnormality of the lateral acceleration sensor was used.

That is, as shown in the claim correspondence diagram of FIG. 1, a lateral acceleration sensor a for outputting a lateral acceleration detection value corresponding to the lateral acceleration of the vehicle by an electric signal, and a wheel speed detecting means b for detecting the left and right wheel rotation speeds. And a lateral acceleration estimation calculation means c for calculating a lateral acceleration estimated value based on the left and right wheel rotation speeds from the wheel speed detection means b, and a difference between the lateral acceleration detected value and the lateral acceleration estimated value is a predetermined value or more. When the state of ## EQU1 ## continues for a predetermined time, the sensor abnormality detecting means d detects that the lateral acceleration sensor a is abnormal, and when a sensor abnormality signal is output from the sensor abnormality detecting means d, a predetermined fail-safe operation is performed. And a fail-safe actuation means e for performing.

(Operation) When the sensor is abnormal, the sensor abnormality detecting means d is in a predetermined state in which the difference between the lateral acceleration detection value from the lateral acceleration sensor a and the lateral acceleration estimation value from the lateral acceleration estimation calculating means c is a predetermined value or more. When the abnormality determination condition of sustaining time is satisfied, a sensor abnormality signal is output, and a predetermined failsafe operation such as issuing an alarm by the failsafe operation means e is performed.

Therefore, the abnormality of the lateral acceleration sensor a applied to various control systems of the vehicle is accurately detected by a cost-effective device that does not use a plurality of sensors, and the control system occurs when the abnormality is left unattended. Can be minimized.

First Embodiment First, the configuration will be described.

FIG. 2 is a braking system to which a torque split control system (driving force distribution control device) of a four-wheel drive vehicle having a lateral acceleration sensor abnormality detection device of the embodiment is applied and a four-wheel antilock brake control system is applied. FIG. 1 is an overall system diagram including a system. First, the configuration of a torque split control system will be described.

The vehicle to which the torque split control system of the embodiment is applied is a rear-wheel-based four-wheel drive vehicle, and its drive system includes an engine 1, a transmission 2, a transfer input shaft 3, a rear propeller shaft 4, a rear differential 5, and a rear differential. It is equipped with wheels 6, transfer output shaft 7, front propeller shaft 8, front differential 9, and front wheels 10. The engine driving force that has passed through the transmission 2 is directly transmitted to the rear wheels 6, and the front wheels drive system to the front wheels 10. Is transmitted via the transfer clutch device 11 provided between the transfer input / output shafts 3 and 7.

A torque split control system that optimally controls the driving force distribution between the front and rear wheels while achieving both driving performance and steering performance is achieved by the transfer clutch device 11 (for example, the Japanese Patent Application No. Sho 63-3253
(See the description and drawings of No. 79), a control oil pressure generator 20 that generates a control oil pressure Pc that is a clutch engagement force, and information from various input sensors 30 to a solenoid valve 28 provided in the control oil pressure generator 20. A torque split control section 40 of the control unit C / U that outputs a predetermined solenoid drive current _IETS based on the above, and an alarm lamp 50 that lights up when various abnormalities occur.

The hydraulic control device 20 controls a motor 22 that is driven or stopped by a relief switch 21, a hydraulic pump 24 that is driven by the motor 22 to suck up from a reservoir tank 23, and a pump discharge pressure (primary pressure) from the hydraulic pump 24. An accumulator 26 that stores via the check valve 25 and a solenoid valve 28 that adjusts the line pressure (secondary pressure) from the accumulator 26 to a predetermined control hydraulic pressure Pc by the solenoid drive current I _ETS from the torque split control unit 40. The control oil Pc is supplied to the clutch port after passing through the control oil pressure pipe 29.

As the various input sensors 30, as shown in the block diagram of the system electronic control system of FIG.
a, right front wheel rotation sensor 30b, left rear wheel rotation sensor 30c, right rear wheel rotation sensor 30d, accelerator opening sensor 30e, lateral acceleration sensor 30
f, a drive current sensor 30g, a control hydraulic pressure sensor 30h, and a front wheel shaft torque sensor 30i.

As shown in the block diagram of the system electronic control system of FIG. 3, the torque split control unit 40 includes a left front wheel speed calculation circuit.
40a, right front wheel speed calculation circuit 40b, left rear wheel speed calculation circuit 40c, right rear wheel speed calculation circuit 40d, front wheel speed calculation circuit 40e, rear wheel speed calculation circuit 40f,
Rotational speed difference calculation circuit 40g, lateral acceleration output value correction circuit 40h, gain calculation circuit 40i, fastening force calculation circuit 40j, dither signal generation circuit 40k, solenoid drive circuit 40l, rotational speed difference output value abnormality detection circuit 40m, lateral acceleration sensor It has an abnormality detection circuit 40n, a clutch abnormality detection circuit 40o, an abnormality determination threshold value circuit 40p, and a fail-safe circuit 40q.

As the alarm lamp 50, as shown in the block diagram of the system electronic control system of FIG. 3, there are a rotational speed difference abnormality alarm lamp 50a, a lateral acceleration sensor abnormality alarm lamp 50b, and a clutch abnormality alarm lamp 50c.

Incidentally, the lateral acceleration sensor abnormality detection device of the embodiment for detecting the abnormality of the lateral acceleration sensor 30f, the left front wheel rotation sensor 30a,
Right front wheel rotation sensor 30b, left front wheel speed calculation circuit 40a, right front wheel speed calculation circuit 40b, lateral acceleration sensor 30f, lateral acceleration sensor abnormality detection circuit 40n, fail safe circuit 40q, and alarm lamp 50b Has been done.

Next, the configuration of the four-wheel antilock brake control system will be described with reference to FIGS. 2 and 3.

The braking system to which the four-wheel anti-lock brake control system of the embodiment is applied is, as shown in FIG. 2, a brake pedal.
60, booster 61, master cylinder 62, actuator 63, wheel cylinders 64a, 64b, 64c, 64d, brake piping 65, 66a, 6
It has 6b, 66c and 66d.

Then, by controlling the braking force so that the slip ratio of each wheel obtained from the vehicle speed and each wheel speed converges to around 0.15 to 0.3, wheel locking is prevented during sudden braking or low μ road braking. Wheel antilock brake control system
The actuator 63 having a three-position switching solenoid valve and a hydraulic pump motor, and a control unit C for outputting to the actuator 63 drive commands for increasing, reducing, and holding the brake fluid pressure based on information from various input sensors 30. / U anti-lock brake control unit 70, and an alarm lamp 50 that lights up in the event of various abnormalities.

The various input sensors 30 may be the longitudinal acceleration sensor 30 as shown in the block diagram of the system electronic control system of FIG.
The left front wheel rotation sensor 30a, the right front wheel rotation sensor 30b, the left rear wheel rotation sensor 30c, the right rear wheel rotation sensor 30d, etc., which have j and bring necessary information are also used as the torque split control system.

As shown in the block diagram of the system electronic control system of FIG. 3, the antilock brake control unit 70 includes a vehicle speed calculation circuit 70a, an antilock control circuit 70b, an actuator drive circuit 70c, a longitudinal acceleration sensor abnormality detection circuit 70d, It has a fail-safe circuit 70e.

The alarm lamp 50 includes a longitudinal acceleration sensor abnormality alarm lamp 50d.

Next, the operation will be described.

FIG. 4 is a flow chart showing the flow of front and rear wheel drive force distribution control operation in the torque split control unit 40, and the flow of control operation will be described in order of steps.

At step 80, the left front wheel rotation speed N _FL and the right front wheel rotation speed N are calculated from the respective wheel rotation sensors 30a, 30b, 30c, 30d and the lateral acceleration sensor 30f.
Sensor signals of _FR , left rear wheel speed N _RL , right rear wheel speed N _RR , and lateral acceleration Yg are read.

In step 81, the left front wheel rotation speed N _FL , the right front wheel rotation speed N _FR , the left rear wheel rotation speed N _RL , the right rear wheel rotation speed read in step 80
Left front wheel speed V _WFL , right front wheel speed V _WFR , left rear wheel speed V _WRL , and right rear wheel speed V _WRR are calculated from each of N _RR .

In step 82, the front wheel speed V _WF is calculated from the left front wheel speed V _WFL and the right front wheel speed V _WFR .

In step 83, the rear wheel speed V _WR is calculated from the left rear wheel speed V _WRL and the right rear wheel speed V _WRR .

In step 84, the front / rear wheel speed difference ΔV _W (= V _WR −V _WF ) is calculated from the front wheel speed V _WF and the rear wheel speed V _WR .

In step 85, the gain K is calculated by the reciprocal of the lateral acceleration correction value Yg '.

In step 86, the clutch engagement force T _M is calculated from the front-rear wheel rotation speed difference ΔV _W , the gain K, and the engagement force calculation formula (the relationship shown in FIG. 5 is shown in the map).

In step 87, the solenoid drive current I _ETS that obtains the clutch engagement force T _M obtained in step 86 is output to the solenoid valve 28.

FIG. 6 is a flowchart showing the flow of the lateral acceleration sensor abnormality detection operation of the first embodiment, which is performed by interrupt processing at regular time intervals (for example, every 10 msec) during the driving force distribution control operation. The flow will be described in order of each step.

In step 90, the left front wheel speed V _WFL , the right front wheel speed V _WFR, and the lateral acceleration detection value Yg are read.

In step 91, the vehicle speed Vi is obtained from the left front wheel speed V _WFL and the right front wheel speed V _{WFR by} the following formula.

Vi = 1/2 (V _WFL + V _WFR ) In step 92, the turning radius R is calculated from MIN (V _WFL , V _WFR ), left front wheel speed V _WFL , right front wheel speed V _WFR and front wheel tread width tr. Is calculated by

The estimation of the turning radius R will be described with reference to FIG. 7. First, the outer wheel speed V _WOUT during turning is Given in. Therefore, if the difference between the left and right wheel rotation speeds obtained by subtracting the inner wheel speed V _WIN from the outer wheel speed V _WOUT is ΔV, In step 93, the left front wheel speed V _WFL and the right front wheel speed V _WFR are compared to determine whether the vehicle is turning left (lateral acceleration occurs in the right direction) or turning right (lateral acceleration occurs in the left direction), and is turned left. When turning, proceed to step 94, and when turning right, proceed to step 95.

At step 94, depending on the vehicle speed Vi and the turning radius R, Is calculated by the following formula.

In step 95, the vehicle speed Vi and the turning radius R are used. Is calculated by the following formula.

In step 96, it is determined whether or not the vehicle speed Vi is equal to or higher than the set vehicle speed Vth corresponding to the sensor failure determination threshold ± G _TH (for example, 0.5G). When Vi ≧ Vth, the routine proceeds to step 97, where V
If i <Vth, proceed to step 98.

In step 97, And the deviation between the detected lateral acceleration Yg epsilon is determined whether the sensor failure determining threshold ± G _TH following values, the process proceeds to step 98 when the epsilon ≦ ± G _TH, when the epsilon> ± G _TH Step 9
Go to 9.

In step 98, the timer value T is set to zero.

In step 99, a process of adding the timer value T by T + 10 (msec) is performed.

In step 100, the timer value T is the set timer value T
₀ (for example, 100 msec) or more is determined, and T <T ₀
If, then go to step 101, and if T ≧ T ₀ , go to step 1
Go to 02.

In step 101, the lateral acceleration sensor 30f is detected as normal.

In step 102, the lateral acceleration sensor 30f detects an abnormality,
A command to turn on the alarm lamp 50b is output.

As described above, the lateral acceleration detection value Yg from the lateral acceleration sensor 30f always outputs a constant value, or when the sensor is abnormal such as outputting the lateral acceleration detection value Yg that changes regardless of the vehicle lateral acceleration. , If the deviation ε between the lateral acceleration detection value Yg and the lateral acceleration detection value Yg exceeds the sensor fail judgment threshold ± G _TH , step 1
From 00 to step 102, the warning lamp 50b is turned on, failsafe operation is performed to inform the driver that the lateral acceleration sensor 30f is abnormal, and then the lateral acceleration sensor 30f is checked or replaced to deal with the sensor abnormality. can do.

Therefore, the lateral acceleration sensor abnormality detection device of the first embodiment has the following features.

Anomaly judgment base Is obtained by calculation based on the signals from the left and right front wheel rotation sensors 30a, 30b provided in advance in the torque split control system, so that the abnormality of the lateral acceleration sensor 30f does not use a plurality of lateral acceleration sensors. It can be accurately detected with a cost-effective device.

If the lateral acceleration sensor 30f is abnormal, the warning lamp 50b is immediately turned on to notify the driver of the abnormality. Therefore, if the abnormality is left as it is, the influence on the torque split control system (for example, lateral acceleration detection (Inappropriate gain K determined by the value Yg will cause insufficient clutch engagement force to allow drive wheel slip to occur, and excessive clutch engagement force to allow tight corner brakes to occur, deterioration of clutch durability, etc.) Can be minimized.

Due to tire malfunction Since the deviation ε from the lateral acceleration detection value Yg appears, even if the tire dynamic radius is extremely different between the left and right due to wear, lack of air pressure, or mounting of different tires, etc., notify the driver by lighting the alarm lamp 50b. You can

Second Embodiment Next, a lateral acceleration sensor abnormality detection device of the second embodiment will be described.

This second embodiment device is the same as the first embodiment device. While the sensor abnormality was detected by the deviation ε between the lateral acceleration detection value Yg and the lateral acceleration detection value Yg, the sensor abnormality is detected by comparing the lateral acceleration estimation area equivalent to the lateral acceleration estimation value with the lateral acceleration detection absolute value | Yg |. This is an example of detection.

Since the device configuration is the same as that of the first embodiment device, the description is omitted.

FIG. 8 is a flow chart showing the flow of the lateral acceleration sensor abnormality detection operation of the second embodiment performed by the interrupt processing at regular time intervals (for example, every 10 msec), and the flow of the detection operation will be described step by step.

In step 110, the left front wheel speed V _WFL , the right front wheel speed V _WFR, and the lateral acceleration detection value Yg are read.

In step 111, the vehicle speed Vi is _calculated by the following equation from the left front wheel speed V _WFL and the right front wheel speed V _WFR .

Vi = 1/2 (V _WFL + V _WFR ) In step 112, the lateral acceleration detection absolute value | Yg | is obtained by taking the sign of the lateral acceleration detection value Yg.

In step 113, the front wheel rotational speed difference ΔV is calculated by the following equation from the left front wheel speed V _WFL and the right front wheel speed V _WFR .

ΔV = | V _WFL + V _WFR | In step 114, it is determined whether the vehicle running state due to the vehicle speed Vi and the front wheel rotation speed difference ΔV is in the high lateral acceleration estimation range.
It is determined by Vi ≧ Vi ₀ and ΔV ≧ ΔV _0. If it is in the high lateral acceleration estimation region, the process proceeds to step 115. Otherwise, the process proceeds to step 117.

In step 115, it is determined whether or not the lateral acceleration detection absolute value | Yg | is less than the set lateral acceleration Ygo. If | Yg | <Ygo, the process proceeds to step 116. If | Yg | ≧ Ygo, the step proceeds to step 116. Proceed to 119.

In step 117, it is determined whether the vehicle running state based on the vehicle speed Vi and the front wheel rotation speed difference ΔV is in the low lateral acceleration estimation range.
It is determined by Vi ≦ Vi ₀ and ΔV ≦ ΔV _0. If it is in the low lateral acceleration estimation range, the process proceeds to step 118, and otherwise, the process proceeds to step 119.

In step 118, it is determined whether or not the lateral acceleration detection absolute value | Yg | exceeds the set lateral acceleration Ygo. If | Yg |> Ygo, proceed to step 116. If | Yg | ≦ Ygo, proceed to step 116. Proceed to 119.

Here, the basis of the sensor abnormality determination of the second embodiment will be described. The relation characteristic between the vehicle speed Vi and the front wheel rotation speed difference ΔV is shown in FIG. 9 with the lateral acceleration as a parameter.

In Fig. 9, when the vehicle speed is 20 km / h or more and the front wheel rotational speed difference is 0.5 km / h or more, the lateral acceleration is 0.05 g or more shown by the solid line characteristic (for example, 0.1 g shown by the dotted line characteristic). Only acceleration can occur.

On the contrary, the vehicle speed is 20km / h or less and the front wheel speed difference is 0.5k.
If it is less than m / h, only lateral acceleration of less than 0.05g can be generated.

Therefore, for example, when the set lateral acceleration Ygo is set to 0.05 g, the set vehicle speed Vi ₀ is set to 20 km / h, and the set front wheel rotational speed difference ΔV ₀ is set to 0.5 km / h as specific numerical values of the reference value, The sensor abnormality can be detected.

In step 116, the timer value T is added by T + 10 (msec).

In step 119, the timer value T is set to 0.

In step 120, the timer value T is the set timer value T
₀ (for example, 100 msec) or more is determined, and T <T ₀
If, then go to step 121, and if T ≧ T ₀ , go to step 1
Proceed to 22.

In step 121, the lateral acceleration sensor 30f is detected as normal.

In step 122, the lateral acceleration sensor 30f detects an abnormality,
A command to turn on the alarm lamp 50b is output.

As described above, the lateral acceleration sensor detection device according to the second embodiment has a feature that the calculation is simple in addition to the features of the device according to the first embodiment.

Although the embodiment has been described above with reference to the drawings, the specific configuration and control contents are not limited to this embodiment.

For example, in the embodiment, the example of the lateral acceleration sensor abnormality detection device applied to the torque split control system in which the left and right front wheel rotation sensors are used as input sensors is shown, but various vehicle-mounted control systems in which the lateral acceleration sensor is used as an input sensor are shown. Of course, it can be applied to, for example, an active suspension control device and a four-wheel steering control device.

Further, in the embodiment, an example in which an alarm lamp is turned on as a fail-safe operation has been shown, but "a warning buzzer sounds", "a control system applied is stopped",
One or a plurality of various fail-safe operations such as “fixing the actuator on the safe side” and “using the estimated value instead of the detected value of the lateral acceleration control information” may be combined.

(Effects of the Invention) As described above, in the lateral acceleration sensor abnormality detection device of the present invention, the lateral acceleration estimated value obtained by calculation based on the wheel rotation speeds of the left and right wheels is used as the basis for the abnormality determination. Since it is a device that detects abnormality of the sensor, the abnormality of the lateral acceleration sensor applied to various vehicle control systems is accurately detected with a cost-effective device, and the control system that occurs when the abnormality is left The effect that the influence can be minimized is obtained.

[Brief description of drawings]

FIG. 1 is a diagram showing a lateral acceleration sensor abnormality detection device according to the present invention, and FIG. 2 is an overall schematic diagram showing a drive system, a braking system and a control system of a four-wheel drive vehicle to which the embodiment device is applied. FIG. 3 is a block diagram showing an electronic control system to which the embodiment apparatus is applied, FIG. 4 is a flowchart showing front and rear wheel driving force distribution control operation, and FIG. 5 is a clutch engagement force characteristic diagram with respect to front and rear wheel rotation speed difference. FIG. 6 is a flowchart showing the flow of the lateral acceleration sensor abnormality detection operation of the first embodiment, FIG. 7 is a theoretical explanatory diagram for estimating the turning radius from the wheel speed, and FIG. 8 is the lateral acceleration sensor abnormality detection of the second embodiment. FIG. 9 is a flow chart showing the operation flow, and FIG. 9 is an explanatory view of the theory of abnormality detection of the lateral acceleration sensor of the second embodiment. a ... Lateral acceleration sensor b ... Steering wheel speed detection means c ... Lateral acceleration estimation calculation means d ... Sensor abnormality detection means e ... Fail-safe actuation means

Claims (1)

[Claims] 1. A lateral acceleration sensor for outputting a lateral acceleration detection value corresponding to a lateral acceleration of a vehicle by an electric signal, a wheel speed detecting means for detecting respective left and right wheel rotation speeds, and a left and right wheel speed detecting means for detecting the lateral acceleration. Lateral acceleration estimation calculation means for calculating an estimated lateral acceleration value based on each wheel rotation speed, and lateral acceleration when a state in which a difference between the detected lateral acceleration value and the estimated lateral acceleration value is a predetermined value or more continues for a predetermined time. A sensor abnormality detecting means for detecting that the sensor is abnormal, and a failsafe operating means for performing a predetermined failsafe operation when a sensor abnormality signal is output from the sensor abnormality detecting means. Lateral acceleration sensor abnormality detection device.