JPH02195224A - Apparatus for detecting steering angle of vehicle - Google Patents

Abstract

PURPOSE:To enhance detecting accuracy by comparing a detected steering angle and an estimated steering angle which are detected by the completely different means of a steering-angle detecting means and a vehicle-speed detecting means, detecting the error in either angle and detecting the error when the difference has continued for a specified time period. CONSTITUTION:At first a register and a memory are initialized by supplying a power source. The output values of a steering angle sensor 2 are counted in a counter 3. Operation is performed in an input/output part 8f in an electronic control device. Thus, the steering angle is obtained. The wheel speed of each wheel is obtained from wheel speed sensors 4 - 7. The speeds of the right and left idler wheels are used, and the steering angle of a vehicle is estimated and operated based on the geometrical model at the time of turning, and the estimated steering angle is obtained. Then, the neutral steering angle is obtained, and the detected angle is corrected to the value from the neutral angle. The value is compared with the estimated steering angle, and the abnormality in steering angle is judged. This operation is repeated, and the corrected detected steering angle is utilized for anti-skid control.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a device for detecting a steering angle of a vehicle and for detecting an error in this steering angle.

[Conventional technology]

2. Description of the Related Art Conventionally, various types of vehicle travel control devices, such as vehicle suspension control devices and vehicle anti-lock control devices, have been proposed in which a steering angle of a vehicle is input and control is performed in accordance with this steering angle.

In particular, as an anti-skid control device,
No. 109789, JP-A-59-70235, JP-A-6
No. 3-49574 and Japanese Patent Application Laid-open No. 63-57359 are known.

Further, as methods for detecting the steering angle, there are known methods in which the steering angle is directly detected from the steering system extending from the steering wheel of the vehicle to the steered wheels, and a method in which the steering angle is detected from the difference in wheel speeds.

[Problem to be solved by the invention]

As described above, when the steering angle of a vehicle is used in various vehicle control devices, the steering angle is required to have high accuracy and high reliability.

However, in the past, no device has been proposed that reliably detects errors in the steering angle, and there is a problem in that the reliability of the steering angle is low in order to perform sufficient control according to the steering angle. Further, there is a problem in that accurate control cannot be performed if an error occurs in the steering angle.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a device that can reliably detect steering angle errors and increase the reliability of steering angles. .

[Means to solve the problem]

In order to achieve the above object, the present invention, as shown in FIG. 1, comprises: wheel speed detection means for detecting left and right wheel speeds of a vehicle; and steering angle detection means for detecting a steering angle from a steering system of a vehicle. and a calculation means for calculating an estimated steering angle based on the difference between the left and right wheel speeds detected by the wheel speed detection means, and a calculation means for calculating an estimated steering angle based on the difference between the left and right wheel speeds detected by the wheel speed detection means, and the estimated steering angle calculated by the calculation means and the detected steering angle detected by the steering angle detection means. A technical means of a steering angle detection device for a vehicle is adopted, which includes a detection means for detecting an error in the detected steering angle or the estimated steering angle when a state in which the difference with the steering angle exceeds a predetermined value continues for a predetermined period of time.

[Function] According to the configuration of the present invention described above, 1. The detected steering angle detected from the steering system of the vehicle is compared with the estimated steering angle calculated from the speed difference between the left and right wheels of the vehicle, and when the difference exceeds a predetermined value and this state continues for a predetermined time, It is determined that the detected steering angle or the estimated steering angle is incorrect.

〔Effect of the invention〕

According to the present invention as described above, the detected steering angle and the estimated steering angle obtained by two completely different means, the steering angle detection means and the wheel speed detection means, are compared, and an error in either of them is detected. The reliability of both the detected steering angle and the estimated steering angle can be increased.

Furthermore, in addition to simply comparing the two, an error is detected when the difference between the two exceeds a predetermined value for a predetermined period of time, which prevents false detections due to response delays or noise. and can ensure high reliability.

〔Example〕

Embodiments to which the present invention is applied will be described below based on the drawings.

This embodiment applies the present invention to an anti-skid control device, which performs anti-skid control according to the detected steering angle detected from the steering system of the vehicle, corrects the neutral steering angle of the detected steering angle, and further This is to detect an error in the detected steering angle or estimated steering angle.

FIG. 2 is a block diagram of this embodiment.

As shown in the figure, the anti-skid control device includes a steering angle sensor 2 which detects the steering angle of the vehicle and outputs a detection signal.
A counter 3 that counts the detection signal of the steering angle sensor 2 and outputs a steering angle signal. Each wheel of the vehicle 4a, 5a, 6a,
, 7a and outputs a wheel speed signal by detecting the rotational speed of the wheels, and an electronic control unit (hereinafter simply referred to as ECU) 8 that centrally controls these.

Further, the anti-skid control device l includes a brake pedal 9
Mask cylinder 9 which generates oil pressure according to the amount of depression of a.
A brake hydraulic actuator to regulates the hydraulic pressure of the mask cylinder 9 under the control of the ECU 3; 6b and 7b.

Further, the anti-kid control device 1 includes a brake switch 1 as a detector that detects the operation of the brake pedal 11.
1. It has a vehicle speed sensor 12 that detects vehicle speed.

As shown in FIG. 3, the steering angle sensor 2 includes a slit plate 2a press-fitted into the steering shaft 20, and two sets of photo ink actuators 2b and 2c disposed at positions sandwiching the slit plate 2a. It is configured. As the steering shaft 20 rotates, the slit plate 2a blocks and transmits light through the optical paths of the photointerrupters 2b and 2c, resulting in steering that is out of phase by the phase difference determined according to the placement positions of both the photointerrupters 2a and 2b. An angle sensor detection signal is output. Therefore, the steering direction and the amount of steering can be detected based on the transition of the output states of the first steering angle sensor detection signal SSI from the photo ink club 2b and the second steering angle sensor detection signal SS2 from the photo ink club 2c.

This steering angle sensor first detection signal SS 1. The steering angle sensor second detection signal S32 is manually input to the counter 3 shown in FIG.

Further, the transmission signal of the counter 3 and the detection signals of each sensor and switch are input to the ECU 3. ECU3 is a CPU
8a, ROM8b, RAM8c.

It is configured as a logic operation circuit centered around a backup RAM 8d, and is connected to an input/output section 8f and an output section 8g via a common bus 8e, and performs input/output with the outside. The wheel speed signal detected by the wheel speed sensor 4.5.6.7 is transmitted via the waveform shaping circuit 8h and the input/output section 8f, the transmission signal of the counter 3 is transmitted, and the detection signal of the vehicle speed sensor 12 is transmitted via the input/output section 8f. and are respectively input to the CPU 8a. On the other hand, the output section 8g,
Brake hydraulic actuator 10 via drive circuit 81
Outputs a control signal to.

Next, the operation of the apparatus shown in FIG. 2 will be explained. Note that a description of the operation regarding the anti-skid control will be omitted, and the neutral steering angle correction process and the steering abnormality detection process will be described.

The device shown in Figure 2 starts operating when power is supplied.
Operation ends when the power is turned off.

When power is supplied to the device, counter 3 has a count value of 0.
The change in the steering angle is counted based on the signal from the steering angle sensor 2, and this count value is output to the ECU 3 as a transmission signal. Therefore, since the steering position at the start of power supply is set to the neutral steering angle, a process for correcting the neutral steering angle is required after power supply is started.

FIG. 4 is a flowchart showing the steering angle calculation process executed by the ECU 3.

When power is supplied to the ECU 3 and step 100 is reached, registers and memory for subsequent arithmetic processing are initialized.

In step 200, a count value indicating the steering angle is input from the counter 3.

In step 300, steering angle calculation processing is performed to convert the count value input from the counter 3 into a steering angle, and the detected steering angle 5
Find TRI (n).

This detected rudder angle 5TRI (n) is calculated from the following equation (1) by the conversion amount of the count value C of the counter 3 to the previous detected rudder angle 5TRI (n-1) (C(n) - C(n-1)) is calculated by adding

5TRI (n)=STR1(n-1)+α(C(n
) -C(n-1) ) ...... (1) α: Coefficient In step 400, the wheel speed signal is input from each wheel speed sensor 4.5°6.7, and in step 500, the wheel speed signal of each wheel is input. Find the speed Vw.

In step 600, among the wheel speeds determined in step 500, the speeds of the left and right idle wheels are set to V, 1L, respectively.
As V□, the steering angle of the vehicle is estimated from the geometric model when the vehicle turns, and an estimated steering angle 5TR2(n) is obtained. This estimated steering angle 5TR2(n) is obtained from the following equation (2).

5TR2(n)=(2・Ks-L/W)(Vwc-V
w*)/(Vwm+VwL)... (2) Ks steering ratio.

L: Wheel base W Nidred V Rudder angle 5TRI (n) and estimated rudder angle 5TR2 (n)
An abnormality in the steering angle is determined by comparing the

Thereafter, steps 200 to 800 are repeated, and the corrected detected steering angle 5TRI (n) is used for anti-skid control.

Next, steps 700 and 800 will be explained in more detail with reference to FIGS. 5 and 6.

Step 71 of the steering angle correction process 700 shown in FIG.
0, it is determined whether or not the steering angle can be corrected, and if the correction is allowed, the subsequent steps are executed; if the correction is not allowed, the process moves to step 800. Conditions for permission of this correction include the following conditions (a) and 3), and a condition is determined that reduces the error in the estimated steering angle determined from the wheel speed. Furthermore, condition (2) is a condition for determining a neutral steering angle, and indicates that the vehicle is traveling substantially straight.

(a) Vehicle speed V≧20h/h (b) Stop lamp switch: Off (C) Parking brake switch: Off (d) Anti-skid control is not in progress.

(e) 1 Idle wheel acceleration 1 < 0.5 G (f) 1 Differential value of estimated steering angle 1 ≦ 10 deg/s (g) 1 Quasi-constant steering angle 1 ≦
5 deg In step 715, the maximum value of the detected steering angle is set to MAX, the minimum value is set to MIN, and sampling is performed every time step 715 is executed. Here, the detected steering angle 5TRI
When (n) becomes larger than the previous MAX or smaller than the previous MIN, MAX or MIN is updated.

In step 720, a processing error in MAX and MIN sampled in step 715 is detected.

That is, if the condition in step 710 is that the detected steering angle 5TRL (n) should show a variation of ±5 degrees due to the smell, but the variation in MAX and MIN is large, it is determined that there is a processing error, and the process branches to step 745.

In step 725, MAX, M according to step 715
It is determined whether sampling of IN is completed. Here, if the difference between MAX and MIN exceeds a predetermined value, it is determined that the process has ended and the process proceeds to step 730.

In step 730, the MA sampled so far is
The average value of X and MIN is obtained from the following equation (3) and the neutral steering angle is estimated.

CNT=(MAX+M1N)/2...-(3
) This equation (3) assumes that the average position of fine steering when the vehicle is traveling substantially straight is the neutral steering angle.
In step 735, the detected steering angle STR1(n) is corrected using the neutral steering angle CNT obtained in step 730 according to equation (4) below.

5TR2(n)=STR2(n)-CNT/K...
... (4) K: Correction number count value Note that in equation (4), the correction amount (CNT/K) is made a function of the correction number count value because the detected rudder angle is changed to the neutral rudder angle at the initial stage of calculation. This is to improve convergence and to suppress large fluctuations in the latter half of the calculation.

In step 740, the number of corrections is counted up. Note that this correction number count value is also used to determine whether or not to use the detected steering angle STR1(n) for anti-skid control, and the detected steering angle 5T after a predetermined number of corrections or more is used.
By using RI (n) for anti-skid control, the reliability of detected steering angle STR1 (n) can be improved.

In step 745, the MAX and MIN values sampled in step 715 are reset to prepare for the next correction process.

By performing the process in step 700, the deviation of the detected steering angle STR1(n) from the neutral steering angle CNT is corrected.

Step 8 of the steering angle abnormality determination process 800 shown in FIG.
In step 10, it is determined whether or not to permit abnormality determination of the steering angle. Here, in addition to the conditions (a) to 2) above, the following (c) is added as a condition when the error in the estimated steering angle 5TR2(n) is small. This corresponds to the fact that when the steering angle is large, the error in the quasi-constant steering angle becomes large depending on the driving condition.

(h) l Steering angle (STR1(n) l <30deg
In step 815, it is determined whether a steering angle error has already been detected and the error flag is turned on or off. If the error flag is off, step 82
Go to 0.

In step 820, the detected steering angle 5TRI(n) and the estimated steering angle 5TR2(n) are compared, and if the absolute difference (Po) is smaller than a predetermined value, the process proceeds to step 825 and the timer counter value CT is cleared. do.

If the absolute value of the above difference is equal to Kt or greater than Kl, the process proceeds to step 830.

In step 830, the value CT of the timer counter and the predetermined value K are
If CT is equal to or larger than KT, the detected rudder angle 5TRI (n) and the estimated rudder angle 5TR2 (
n) is greater than a predetermined value, and this state has continued for a predetermined period of time, it is determined that the detected steering angle is incorrect, and the process proceeds to step 840, where the error flag is turned on.

On the other hand, in step 830, if CT is smaller than KT, the process proceeds to step 835, where the timer counter value CT
Add.

In this way, the detected steering angle STR1(n) and the estimated steering angle 5T
Based on the comparison with R2(n), the detected steering angle 5TRI(n
) is determined to be incorrect, the error flag is turned on, and the use of the detected steering angle 5TRI (n) for anti-skid control is prohibited. Furthermore, when the error flag is turned on, anti-skid control that does not use the steering angle is performed.

When the error flag is turned on, the process advances from step 815 to step 845 from the next process.

In step 845, the detected rudder angle 5TRI (n) and the estimated rudder angle 5TR2 (n) are compared, and if the absolute value of the difference between them is smaller than a predetermined value of 2, the detected rudder angle 5TRI (In) is compared.
It is determined that there is no error, the timer counter value CT is cleared in step 850, and the error flag is turned off in step 855.

Further, if the absolute value of the above difference is equal to the predetermined value 2 or larger than K, it is determined that the error in the detected steering angle 5TRI (n) continues, and the error flag is kept on.

Even if an error in the -carrier detection steering angle STR1(n) is detected in this way, if the error is resolved again, the error flag is turned off and anti-skid control according to the steering angle is restarted.

Note that Kt in step 820 and 3 in step 845
is set to +>Kg in order to provide hysteresis in the determination.

In addition, in the embodiment described above, when correcting the neutral steering angle, the average of the maximum value and the minimum value of the detected steering angle when the vehicle is traveling almost straight is regarded as the neutral steering angle. The angle correction method is not limited to this, and various methods disclosed in, for example, Japanese Patent Laid-Open Nos. 176804-1982 and 28811-1980 can be employed.

Further, the steering angle sensor according to the present invention can also be used in a device that does not require correction of neutral steering by providing a slit for detecting the neutral position and a photo ink plater in the steering angle sensor to improve the mounting accuracy of the slit plate to the steering shaft. Error detection is effective.

Furthermore, in the above embodiments, the present invention was applied to an anti-skid device, but since the anti-skid device is equipped with a wheel speed sensor, it is relatively easy to apply the present invention. Therefore, the present invention is applicable not only to an anti-skid device but also to a variety of vehicle control devices such as a vehicle day control device that suppresses slips during starting and acceleration, and a suspension control device.

According to the embodiments described above, the reliability of the steering angle can be improved in a vehicle control device that uses the steering angle as one of the input signals, and it is possible to introduce more advanced and complicated control. can.

Furthermore, if an error occurs in the steering angle, it can be reliably detected and countermeasures can be taken by the vehicle control device, thereby improving the reliability of the vehicle control device.

Particularly in systems that are conventionally equipped with wheel speed sensors, such as anti-skid control devices, it is possible to perform control according to the steering angle with high accuracy and reliability with a small increase in cost.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing the configuration of the present invention, Fig. 2 is a block diagram of an embodiment to which the present invention is applied, Fig. 3 is a perspective view showing a steering angle sensor, Figs. FIG. 6 is a flowchart showing the operation of an embodiment to which the present invention is applied. l...Anti-skid control device, 2...Steering angle sensor, 2a...Slit plate, 2b, 2c...
Photo ink labeler, 3... Counter, 4, 5, 6.
7...Wheel speed sensor, 8...Electronic control unit (EC
U), 9... Mask cylinder, 10... Brake hydraulic actuator, 11... Brake switch, 12
...Vehicle speed sensor.

Claims (1)

[Scope of Claims] 1. Wheel speed detection means for detecting the left and right wheel speeds of a vehicle; steering angle detection means for detecting a steering angle from a steering system of the vehicle; and left and right wheel speeds detected by the wheel speed detection means. a calculation means for calculating an estimated steering angle based on the difference between the steering angles; A steering angle detection device for a vehicle, comprising: detecting means for detecting an error in the detected steering angle or the estimated steering angle when the steering angle continues.