JPH087077B2 - Vehicle status detector judgment device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle state detector determining device for determining whether or not a detector such as a yaw rate sensor or a steering angle sensor for detecting a physical quantity related to a turning state of a vehicle is abnormal. .

[0002]

2. Description of the Related Art Conventionally, for example, Japanese Patent Laid-Open No. 60-124572.
As disclosed in the publication, there is known a device for controlling the turning amount of rear wheels based on signals from an angular velocity (yaw rate) sensor and a steering angle sensor. In addition to the above, various devices have been proposed for controlling the traveling state of the vehicle based on the yaw rate signal or the steering angle signal for the purpose of improving the maneuverability and traveling stability of the vehicle.

[0003]

If an abnormality occurs in the yaw rate sensor or the steering angle sensor and an erroneous signal is output, when the running state of the vehicle is controlled based on these signals, the desired control is performed. Not only can it not be done, but there is a high possibility that the vehicle behavior will be adversely affected. Therefore, conventionally, whether the output value of the sensor is within the specified range, or whether the sensor output signal has changed at a rate of change that cannot occur in a normal state, etc. is monitored, and an abnormality in the sensor output signal is detected. Is being detected.

However, such a detection method has a problem in that, for example, an anomaly in which the sensor output signal does not change or an anomaly in which the sensor output signal includes an excessive offset component cannot be detected. As another method for detecting the yaw rate, Japanese Patent Laid-Open No. 63-218866 proposes to calculate the yaw rate from the speed difference between the left and right driven wheels of the vehicle. However, this method cannot calculate an accurate yaw rate, for example, when steering at a large steering angle, when the steering speed is fast, or when the wheels are slipping. That is, there is a problem that an incorrect yaw rate may be calculated depending on the running state of the vehicle.

The present invention has been made in view of the above points, and improves the accuracy of determination of an abnormal state of a detector such as a yaw rate sensor or a steering angle sensor that detects a physical quantity related to a turning state of a vehicle, and thus a detector. It is an object of the present invention to provide a vehicle state detector determination device capable of improving the accuracy of a detection value by the vehicle.

[0006]

In order to achieve the above object, a vehicle state detector determining device according to the present invention, as shown in FIG. 1, includes a detector for detecting a physical quantity related to a turning state of a vehicle, and a vehicle. Speed detecting means for respectively detecting the speeds of the left and right wheels, calculating means for calculating an estimated value of a physical quantity relating to the turning state of the vehicle based on the speed difference between the left and right wheels respectively detected by the speed detecting means, and the detecting means. Determination means for determining the presence or absence of an abnormality of the container by comparing the detected physical quantity with the calculated physical quantity, a driving state detecting means for detecting the driving state of the vehicle, and the driving state detecting means. A determination unit that determines whether or not the operating state of the vehicle is in a state in which the estimated value of the physical quantity calculated by the calculation unit includes an error, and the determination unit includes an error. When on purpose it is determined, and a prohibiting means for prohibiting the judgment of the judging means.

[0007]

With the above structure, the physical quantity detected by the detector is compared with the estimated value of the physical quantity calculated from the speed difference between the left and right wheels of the vehicle, and it is determined whether the detected physical quantity is abnormal. It Therefore, for example, an abnormality such as a physical quantity detected by the detector that does not change, or an abnormality including an offset component can be detected without omission.

Further, when it is determined that the estimated value of the physical quantity calculated from the speed difference between the left and right wheels includes an error based on the driving state of the vehicle, the above determination process is prohibited. For this reason, it is possible to prevent the detected physical quantity from being erroneously determined to be abnormal from the incorrect estimated value of the physical quantity.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 2 shows the configuration when the present invention is applied to a rear wheel steering system. In FIG. 2, a DC servomotor 2 installed in the rear wheel steering mechanism 1 is an electronic control unit (EC
U) 3 receives the command signal, rotates in the forward and reverse directions, and is connected to one end of the input shaft (torsion bar, not shown) of the rack and pinion mechanism with hydraulic power assist, that is, the steering mechanism 1 through the reduction gear 4. A pinion gear 5 is attached to the other end of the torsion bar and meshes with a rack 7 formed at one end of a power piston 6. That is, one end of the torsion bar is rotated by the motor 2, the torsion bar is twisted, the throttle area of the hydraulic valve 8 is changed, the torsion bar is twisted, the throttle area of the hydraulic valve 8 is changed, and the twist of the torsion bar is corrected. It is a mechanism that supplies hydraulic pressure in the direction to move the power piston 6.

Both ends of the power piston 6 are connected to a knuckle arm 10 via tie rods 9, respectively. The rear wheel 11 is supported by the knuckle arm 10 so as to be swingable in the left-right direction. Therefore, when the power piston 6 moves in the direction of arrow A in the figure, the rear wheel 11 is steered left and right. When the torsion bar is no longer twisted, the throttle area of the hydraulic valve 8 becomes "0" and the hydraulic pressure for moving the power piston 6 becomes "0".
Will stop. Here, the rear wheel steering angle sensor 12 detects the position of the power piston 6 and outputs a signal. ECU3
Calculates the rear wheel actual steering angle from the relationship between the position of the power piston 6 and the rear wheel actual steering angle based on this signal.

A steering mechanism 1 including a servo motor 2 and an ECU
3 configures a positioning servo system that controls the positioning of the rear wheel 11 so that the rear wheel actual steering angle matches the rear wheel steering angle command position. Incidentally, 13 is a hydraulic pump for supplying hydraulic pressure to the power piston 6 via the hydraulic valve 8, and 14 is an oil tank. The vehicle speed sensor 15 detects the rotational speed of the axle or the wheel and outputs a vehicle speed signal corresponding to the vehicle speed V to the ECU 3
Output to. The front wheel steering angle sensor 16 is composed of an incremental type rotary encoder, and is provided on a steering shaft 17 as a rotated body. Then, the rotation of the steering shaft 17 associated with the operation of the steering wheel 18 is detected to detect the steering angle θ of the front wheels 19.
A front wheel steering angle signal corresponding to s is output to the ECU 3. The yaw rate sensor 20 is composed of a gyro or the like, and outputs a yaw rate signal corresponding to the rotational angular velocity (yaw rate Wa) of the vehicle around the center of gravity of the vehicle to the ECU 3. The left wheel speed sensor 21 is the rotation speed of the left wheel of the front wheel 19 (left wheel speed ω _l ).
The right wheel speed sensor 22 detects the rotation speed of the right wheel of the front wheels 19 (right wheel speed ω _R ). Brake switch 2
3 is turned on when ABS (anti-lock brake system) control is being executed or when the brake pedal is operated.

The ECU 3 will be described with reference to FIG.
The CU 3 includes a microcomputer (hereinafter, referred to as a microcomputer) 24, waveform shaping circuits 25 to 28, an analog buffer 29, an A / D converter 30, a digital buffer 31, and a drive circuit 32. The waveform shaping circuits 25 to 28 include a vehicle speed sensor 15 and a left wheel speed sensor 2
1, the signals from the right wheel speed sensor 22 and the front wheel steering angle sensor 16 are waveform-shaped and input to the microcomputer 24. Further, the analog buffer 29 takes in each signal from the rear wheel steering angle sensor 12 and the yaw rate sensor 20, and the A / D converter 30 performs analog / digital conversion. The digital buffer 31 latches the signal from the brake switch 23. Further, the drive circuit 32 supplies a current corresponding to the current command value signal If from the microcomputer 24 to the DC servo motor 2.

Next, the operation of the rear wheel steering system thus constructed will be described. 4 shows a main routine of the microcomputer 24, and FIG. 5 shows a vehicle speed sensor and left and right wheel speed sensors 21,
FIG. 6 shows a vehicle speed pulse process that is interrupted by a pulse signal from 22. FIG.
Shows an interrupt processing routine executed every time.

As shown in FIG. 4, the microcomputer 24 is initialized at step A10 at the time of startup, and various processes are repeated at step A20. On the other hand, as shown in FIG. 5, in step B10, the microcomputer 24 calculates and stores the vehicle speed pulse width from the time when the previous pulse interruption occurred and the time when this interruption occurred.

Then, as shown in FIG. 6, from C10 to C
The steps up to 80 are processed every predetermined time (for example, every 5 ms). The microcomputer 24 determines the vehicle speed V from the vehicle speed pulse width stored in the vehicle speed pulse interrupt processing in step C10.
To calculate. Similarly, for the left wheel speed sensor 21 and the right wheel speed sensor 22, the wheel speeds ω _L and ω _{R on} the left and right of the front wheel 19 are calculated from the wheel speed pulse width. Although the vehicle speed V is obtained by the vehicle speed sensor 15 in the present embodiment, the vehicle speed V is calculated from the left and right wheel speed sensors 21 and 22 by (ω _L +
It may be determined as ω _R ) / 2.

The microcomputer 24 fetches the A / D conversion data from the rear wheel steering angle sensor 12 and the yaw rate sensor 20 through the A / D converter 30 in step C20, and in step C30, obtains the rear wheel actual steering angle θr and the actual yaw rate Ws. calculate. Next, in step C40, the brake switch 2
The signal from 3 is taken in via a digital buffer.

Then, in step C50, the number of pulses output from the front wheel steering angle sensor 16 is counted to calculate the front wheel steering angle (steering wheel angle) θs. In step C60, the steering speed θ _v is calculated from the front wheel steering angle θs calculated in this process and the front wheel steering angle θs ₋₁ calculated in the previous process. In step C70, abnormality determination processing of the yaw rate sensor 20 and the front wheel steering angle sensor 16 is performed. The contents will be described with reference to FIGS. 7 to 10.

FIG. 7 is a block diagram showing an outline of the abnormality determination processing of the yaw rate sensor 20. In block D1,
Based on the left and right wheel speeds ω _L and ω _R calculated in step C10 of the flowchart of FIG. 6, the estimated yaw rate γ is calculated by the following equation.

[0019] In block D3, it is determined whether or not the calculated estimated yaw rate γ is used for the abnormality determination process, based on various information related to the driving state of the vehicle. This is because the estimated yaw rate γ calculated from the left and right wheel speeds ω _L and ω _R may include an error depending on the driving state of the vehicle.

Here, an example of the judgment conditions is shown below.

[0021]

[Equation 2] C ₁ ≤ω _L ≤C ₂

[0022]

## EQU3 ## C ₁ ≤ω _R ≤C ₂

[0023]

[Formula 4] C ₁ ≤ V ≤ C ₂

[0024]

[Equation 5] | γ | ≦ C ₃

[0025]

[Equation 6] | ω _L ′ | ≦ C ₄ (∵ω _L ′ is the left wheel acceleration)

[0026]

[Equation 7] | ω _R ′ | ≦ C ₄ (∵ω _R ′ is the acceleration of the right wheel)

[0027]

[Equation 8] | V ′ | ≦ C ₅ (∵V ′ is vehicle acceleration)

[0028]

[ Equation 9] | θ _V | ≦ C ₆ (∵ θ _V is the steering speed)

[0029]

[Formula 10] Brake switch OFF C _{1 to} C ₆ are predetermined constants. However, C
_The values of ₃ and C ₆ may be changed according to the vehicle speed V as shown in FIGS. 11 and 12. Each condition determines whether or not the vehicle driving condition is such that an accurate estimated yaw rate γ can be calculated from the left and right wheel speeds ω _L and ω _R based on Equation 1. That is, each of the above conditions indicates a vehicle operating state in a range in which the vehicle can be treated as a vehicle model in a linear region.

Regarding the vehicle speed V and the wheel speeds ω _L and ω _R , conditions are set so that the estimated yaw rate γ is used for the abnormality determination processing only when the vehicle speed signal itself can be accurately treated as the vehicle speed. It is set. In other words, for example, at the time of braking, the wheel speed ω _L that is different from the speed of the vehicle,
ω _R may be calculated, and the estimated yaw rate γ calculated in this case may include an error. Therefore, the OFF state of the brake switch 23 is set as one of the conditions. Further, due to the structure of the sensor, the number of pulses sent from the sensor decreases at extremely low speeds. Therefore, the cycle of calculating the wheel speed becomes long, and the estimated yaw rate γ may transiently have an error such as when the changes in the left and right wheel speeds ω _L and ω _R are not synchronized. In order to prevent this, the low speed side limit value C ₁ is provided for the left and right wheel speeds ω _L , ω _R detected by the wheel speed sensors 21, 22. Further, due to the problem of the calculation accuracy of the microcomputer 24, the problem similar to that at the time of low speed may occur, such as the resolution becoming worse as the speed becomes higher. Therefore, in addition to the limit value C ₁ on the low speed side, the limit value C ₂ on the high speed side is provided.

A block D2 represents a switch for receiving whether or not the estimated yaw rate γ is used for the abnormality determination process in response to the determination result in the block D3. When the estimated yaw rate γ is not used in the abnormality determination processing, the yaw rate Wa detected at that time is also excluded from the data used in the abnormality determination processing. This is because it is meaningless as an abnormality determination unless the yaw rates detected or estimated at the same time are compared. The block D4 is subjected to an averaging process for calculating an average value for each of the yaw rate Wa and the estimated yaw rate γ in a predetermined time. In block D5, a determination process as to whether or not the yaw rate sensor 20 is abnormal is performed using the average value calculated in block D4.

FIG. 8 is a flow chart for realizing the function shown in FIG. In step E1, the above-mentioned formula 1
Based on the above, the estimated yaw rate γ is calculated. In step E2, the driving state of the vehicle is determined based on the above-mentioned formulas 2 to 10. At this time, if all the conditions are satisfied, the process proceeds to step E3. On the other hand, each equation 2 to 1
If even one of 0 is not established, the sensor abnormality determination routine is exited. In step E3, the averaging process is performed for each of the estimated yaw rate γ and the yaw rate Wa. That is, in step E3, for example, the average values for a predetermined time are calculated as the estimated yaw rate average value γ _avg and the yaw rate average value Wa _avg , respectively.

At step E4, it is determined whether or not the predetermined time has elapsed, and if not, it is determined that the average values γ _avg and Wa _avg have not been calculated, and the routine exits. On the other hand, when it is determined that the predetermined time has elapsed, the routine proceeds to step E5. Steps E5 to E
Step 10 is a process for determining an abnormality in which the yaw rate Wa does not change, and steps E11 to E15 are the yaw rate W.
a is a process of determining an abnormality having an abnormal offset component.

At step E5, the yaw rate sensor 20
It is determined whether or not the absolute value of the difference between the current detected value Wa _i and the previous detected value Wa _i−1 is less than or equal to the predetermined value C7.
At this time, if it is determined that the value is larger than the predetermined value C7, it is determined that at least the abnormality in which the detection value of the yaw rate sensor 20 does not change has occurred, and the process proceeds to step E8.
In step E8, both flags FF1 and F1 are set to 0, and then the process proceeds to step E11.

On the other hand, the detected value Wa of the yaw rate sensor 20
When it is determined that the change of is smaller than the predetermined value C7, the process proceeds to step E6. In step E6, in order to determine whether the abnormality in which the sensor detection value does not change is occurring or the traveling state such as the straight traveling state, the absolute difference between the previous value γ _{i-1 of the} estimated yaw rate and the current value γ _i is determined. Value is the predetermined value C8
Whether or not it is determined (∵C ₇ ≤C ₈ ). As a result, when it is determined that the value is equal to or greater than the predetermined value C _8, it is determined that the sensor detection value does not change because the yaw rate Wa hardly changes even though the estimated yaw rate γ changes. Then, the process proceeds to step E7, and the flag FF1 = 1 is set. In step E9, in order to prevent erroneous determination due to noise or the like, the state in which the flag FF1 = 1 is set is
It is determined whether or not the number of times reaches a predetermined number of times in a row. As a result, when it is determined that the predetermined number of times has been reached, it is determined that the sensor detection value has not changed, and the abnormality determination flag F1 = 1 is set in step E10. Step E6, Step E
When the determination result in 9 is NO, the process proceeds to step E11.

[0036] At step E11, the absolute value of the difference between the estimated yaw rate average gamma _avg and yaw rate average value Wa _{av g} is determined whether a predetermined value C ₉ or higher. This difference is the offset component of the yaw rate Wa, and when this offset component is greater than or equal to the predetermined value C ₉ , the process proceeds to step E12, and the flag FF2 = 1 is set as the offset abnormality. In this case also, in order to prevent erroneous determination, the flag FF is set in step E14.
It is determined whether or not the state of 2 = 1 has occurred a predetermined number of times in succession. As a result, when it is determined that the yaw rate sensor 20 has occurred in succession a predetermined number of times, it is determined that the yaw rate sensor 20 has an offset abnormality, and in step E15, the offset abnormality flag F2 =
Set to 1. If the determination results in steps E11 and E14 are NO, then both flags FF2 and F2 are set to 0 in step E13.

As described above, by comparing the yaw rate Wa with the estimated yaw rate γ estimated from the wheel speeds ω _L and ω _R , the abnormality of the yaw rate sensor 20 can be quickly determined without erroneous determination. Next, FIGS. 9 and 10 show a block diagram and a flow chart showing an outline of the abnormality determination of the front wheel steering angle sensor 16.

Since the front wheel steering angle sensor 16 also performs substantially the same processing as the abnormality determination processing of the yaw rate sensor 20 described above, only different processing will be described below. A block F1 in FIG. 9 is for correcting a phase shift between the estimated steering angle θr calculated in the block F2 from the left and right wheel speeds ω _L and ω _R and the front wheel steering angle θs detected by the front wheel steering angle sensor 16. Is. Specifically, the front wheel steering angle θs detected by the front wheel steering angle sensor 16 is calculated so as to have, for example, a first-order lag transfer characteristic. In order to improve the accuracy, the transfer characteristic of the second-order delay may be provided, but an example approximated by the transfer characteristic of the first-order delay will be described here.

The corrected front wheel steering angle θ's whose phase is corrected by the transfer characteristic of the first-order lag can be obtained by the following equation.

[0040] The time constant is a constant derived from the specifications of the vehicle.
The determination conditions in the block F7 are almost the same as the conditions used for the abnormality determination process of the yaw rate sensor 20 described above. However, the estimated steering angle θr is used instead of the estimated yaw rate in Conditional Expression 5, and when the estimated steering angle θr is within a predetermined range, the estimated steering angle θr is used to make an abnormality determination. That is, the condition is

[0041]

[Equation 12] | θr | <C ′ ₃ At this time, C ′ ₃ may be a constant or a value that changes according to the vehicle speed as shown in FIG. In block F2, based on the left and right wheel speeds ω _L and ω _R , the estimated steering angle θr
To calculate.

[0042] As shown in Expression 13, the estimated steering angle θr is calculated from the left and right wheel speeds ω _L and ω _R , the vehicle speed V, and the vehicle specifications. The stability factor K is the understeer of the vehicle,
It is a constant that represents the characteristics of oversteer and is also measured during actual driving.

The processing in the flowchart of FIG.
It is almost the same as the flowchart of FIG.
Then, the estimated steering angle θr is calculated based on Expression 13, and in step G2, the phase correction of the front wheel steering angle θs is performed based on Expression 11. In step G3, if all the conditions relating to the driving state of the vehicle are satisfied, averaging processing is performed for each of the estimated steering angle θr and the corrected front wheel steering angle θ ′s in steps G4 and G5.

Then, similar to the abnormality determination and processing for the yaw rate sensor 20, steps G6 to G1 are performed.
At 1, it is determined whether or not the output of the front wheel steering angle sensor 16 does not change. Further, in steps G12 to G16, the offset abnormality of the front wheel steering angle sensor 16 is determined. As described above, in step C70 of FIG. 6, the yaw rate sensor 20 and the front wheel steering angle sensor 16 are
The abnormality determination process of is executed.

If it is determined in step C70 that the sensors 16 and 20 are not abnormal, step C80
Then, the rear wheel command steering angle θr ^* is calculated based on the traveling state of the vehicle, for example, by the following equation.

[0046]

[Equation 14] θr ^* = K ₁ (V) · θs + K ₂ (V) · W
a K ₁ and K ₂ are variables that change depending on the vehicle speed V. When it is determined in step C70 that the front wheel steering angle sensor 16 is abnormal, only the terms not including the front wheel steering angle θs in Formula 14 are used to determine the rear wheel command steering angle. θr ^* is calculated.
In this case, the characteristic of the variable K ₂ (V) in Expression 14 may be changed and the rear wheel command steering angle θr ^* may be calculated as in the following expression.

[0047]

[Mathematical formula-see original document] θr ^* = K ₂ ′ (V) · Wa In step C70, when it is determined that the yaw rate sensor 20 is abnormal, the rear wheel command steering angle θr ^* is calculated only from the term that does not include the yaw rate Wa in Expression 14 ^. To calculate. Also in this case, the characteristic of the variable K ₁ (V) in Expression 14 may be changed and the rear wheel command steering angle θr ^* may be calculated as in the following expression.

[0048]

[Mathematical formula-see original document] θr ^* = K ₁ ′ (V) · θs Coefficients K ₁ (V) and K in Equation 14 shown in FIGS.
₂ (V) and coefficients K ₁ ′ (V) and K ₂ ′ whose characteristics have been changed
An example of (V) is shown. Normally, the variable K ₁ (V) is set as an anti-phase term with respect to the front wheel steering angle θs as shown in FIG. 14, and K ₂ (V) is set as an in-phase term as shown in FIG. However, when the front wheel steering angle sensor 16 is abnormal, the rear wheel command steering angle θr ^* is calculated only from the yaw rate term, so that the coefficient K _{2 of the} yaw rate Wa is calculated as shown in FIG.
'(V) is lowered slightly to reduce the feeling of understeer of the vehicle. Further, when the yaw rate sensor 20 is abnormal, only the front wheel steering angle term is present, so the rear wheel command steering angle θr ^*.
Will be calculated only from the anti-phase term, and the vehicle will become unstable. Therefore, when the yaw rate sensor is abnormal,
As shown in, the coefficient K ₁ ′ (V) is set as the in-phase term, and the rear wheel command steering angle θr ^* is calculated as the in-phase term with respect to the front wheel steering angle θs, thereby ensuring the stability of the vehicle. There is.

When either or both of the front wheel steering angle sensor 16 and the yaw rate sensor 20 are determined to be abnormal, the rear wheel command steering angle θr ^* is fixed to the command steering angle at the time of the determination, and then the rear wheels are fixed. The control may be stopped. Further, when the calculation formula of the rear wheel command steering angle θr ^* is switched, the rear wheel steering angle may be gradually changed so as not to change suddenly.

In step C90 of FIG. 6, step C8
Based on the rear wheel command steering angle θr ^* calculated at 0 and the rear wheel command steering angle θr calculated at step C30, a known rear wheel positioning servo calculation is performed so that the difference between the two is zero. Then, in step C100, the motor current command value If is calculated based on this calculation result, and is output to the drive circuit 32 to drive the servo motor 2.

In this embodiment, the yaw rate sensor,
The determination as to whether or not the detection value of the front wheel steering angle sensor is outside the output specification range and the abnormality determination related to the sudden change in the output value are omitted as well known, but these abnormality determinations may also be performed.

[0052]

As described above, according to the present invention,
It is possible to detect abnormalities in which the physical quantity detected by the detector does not change and abnormalities including offset components, and to prevent erroneous determinations during abnormality determinations, so yaw rate sensors, steering angle sensors, etc. It is possible to improve the accuracy of determining the abnormal state of the detector that detects the physical quantity related to the turning state of the vehicle. As a result, it is possible to obtain a detection value with higher accuracy than the above detector.

[Brief description of drawings]

FIG. 1 is a diagram corresponding to a claim of the present invention.

FIG. 2 is an overall configuration diagram of an embodiment of the present invention.

FIG. 3 is a configuration diagram of the electronic control device of FIG. 2.

FIG. 4 is a flowchart showing a main routine of the electronic control unit.

FIG. 5 is a flowchart showing vehicle speed pulse processing.

FIG. 6 is a flowchart of interrupt processing performed at predetermined time intervals.

FIG. 7 is a block diagram showing an outline of a yaw rate sensor abnormality determination process.

FIG. 8 is a flowchart showing a procedure of abnormality determination processing of a yaw rate sensor.

FIG. 9 is a block diagram showing an outline of abnormality determination processing of a front wheel steering angle sensor.

FIG. 10 is a flowchart showing a procedure of abnormality determination processing of a front wheel steering angle sensor.

FIG. 11 is a characteristic diagram of variables that define conditions for performing abnormality determination processing.

FIG. 12 is a characteristic diagram of variables that define conditions for performing abnormality determination processing.

FIG. 13 is a characteristic diagram of variables that define conditions for performing abnormality determination processing.

FIG. 14 is a characteristic diagram showing characteristics of coefficients when a rear wheel command steering angle is calculated.

FIG. 15 is a characteristic diagram showing characteristics of coefficients when a rear wheel command steering angle is calculated.

FIG. 16 is a characteristic diagram showing characteristics of coefficients when calculating a rear wheel command steering angle.

FIG. 17 is a characteristic diagram showing characteristics of coefficients when a rear wheel command steering angle is calculated.

[Explanation of symbols]

 1 Rear Wheel Steering Mechanism 2 Servo Motor 3 Electronic Control Unit 11 Rear Wheel 12 Rear Wheel Steering Angle Sensor 15 Vehicle Speed Sensor 16 Front Wheel Steering Angle Sensor 19 Front Wheel 20 Yaw Rate Sensor 21 Left Wheel Speed Sensor 22 Right Wheel Speed Sensor 23 Brake Switch

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Hiroyuki Hirano, 1-1, Showa-cho, Kariya city, Aichi prefecture, Nihon Denso Co., Ltd. (72) Inventor, Hiroshi Ogura, 1-1, Showa-cho, Kariya city, Aichi prefecture Incorporated (72) Inventor Hitoshi Iwata 1 Toyota-cho, Toyota-shi, Aichi Toyota Automobile Co., Ltd. (56) Reference JP-A-60-124572 (JP, A)

Claims (1)

[Claims] 1. A detector for detecting a physical quantity relating to a turning state of a vehicle, a speed detecting means for detecting respective speeds of left and right wheels of the vehicle, and a speed difference between the left and right wheels respectively detected by the speed detecting means. A calculating means for calculating an estimated value of a physical quantity relating to a turning state of the vehicle; a judging means for judging the presence or absence of abnormality of the detector by comparing the detected physical quantity with the calculated physical quantity; A driving state detecting means for detecting a driving state and a judgment for determining whether or not the driving state of the vehicle detected by the driving state detecting means includes an error in the estimated value of the physical quantity calculated by the calculating means. Means for inhibiting the determination by the determining means when the determining means determines that an error is included. State detector determining device.