JPH10274520A - Steering angle detecting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect sensor abnormality correctly by providing a plurality of steering angle sensors, and detecting the state change of these sensors. SOLUTION: First to third steering angle sensors 22A-22C are parallel provided in a row in optional positions opposed to steering angle detecting through- holes 21a of a sensor disc 21 so as to output steering angle detection pulse signals P1-P3 with phase difference of 60 deg. by the rotation of the sensor disc 21. By detecting whether or not the rising or falling state change is generated to the respective detection signals P1-P3, in the case of the state change being generated to at least two steering angle detection pulse signals, a steering state can be judged. In this state, when the state change is not generated to the remaining steering angle detection pulse, it can be so judged that abnormality such as severance of wire is generated to a steering angle sensor system outputting this steering angle detection pulse. Sensor abnormality can therefore be detected correctly.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steering angle detecting device for detecting a steering angle in a steering system of a vehicle, and more particularly to an auxiliary steering device for assisting at least one of a front wheel and a rear wheel in accordance with the steering of the steering system. The present invention relates to a steering angle detection device suitable for being applied to an active suspension or the like.

[0002]

2. Description of the Related Art A conventional steering angle detecting device is disclosed in, for example, Japanese Patent Application Laid-Open No. 2-29976 (hereinafter simply referred to as a conventional example).

In this conventional example, a disk-shaped sensor disk fixed to a steering shaft is provided, and a first sensor unit and a second sensor unit each including a light emitting diode and a photo IC fixed to a vehicle body are provided. It has a steering wheel steering angle sensor and a steering wheel neutral position detection sensor having the same configuration, and the sensor disk has a steering angle detection slit opened at intervals of several degrees over the entire circumference thereof,
A neutral position detecting slit is formed inside the steering angle detecting slit in a range of, for example, 20 °, and the first sensor unit and the second sensor unit are arranged at half pitch intervals corresponding to the steering angle detecting slit of the sensor disk. As shown in FIG. 10, the phase is set to 90 from the steering angle sensor.
The first and second square pulse signals P1 and P2 which are shifted by ° are output, the square pulse signals are counted to detect the steering angle, and the neutral position detecting sensor detects the presence or absence of the slit for detecting the neutral position. A steering angle detection device that detects a neutral position is described.

[0004] The steering wheel neutral position detection sensor is based on the steering angle detection value of the steering wheel steering angle sensor when the steering wheel reaches the one end of the neutral position detecting slit and is turned on while steering in the same direction. Normal when the value obtained by subtracting the steering angle detection value of the steering wheel angle sensor when the steering wheel reaches the other end and is turned off is within an allowable range obtained by adding an allowable value to the angle of the neutral position detecting slit. Is determined, and when it is out of the allowable range, it is determined to be abnormal.

[0005]

However, in the conventional steering angle detecting device, the first sensor section and the second
By outputting the first and second square pulse signals P1 and P2 having a phase shift of 90 ° from the sensor unit, the steering direction and the steering angle are determined based on the first and second square pulse signals P1 and P2. However, if an error such as a disconnection occurs in one of the first sensor unit and the second sensor unit and the square pulse signal is fixed to the OFF state, the second sensor unit can be detected. When the steering angle is calculated based on the square pulse signals P1 and P2 of the first sensor unit and the second sensor unit, the steering angle of the constant value is calculated even though the steering hole is steered, and the square pulse signal is calculated. It is not possible to detect an abnormality of the sensor from the presence or absence of the pulse signal, and it is not possible to detect a pulse signal having a period finer than the first and second rectangular pulse signals P1 and P2. There is an unsolved problem that the abnormality determination cannot be performed using another pulse signal as in the neutral position sensor, and the first sensor unit and the second sensor unit must be determined to be normal. .

Therefore, the present invention has been made in view of the above-mentioned unsolved problems of the prior art, and it is possible to easily detect an abnormality of a steering angle sensor and to provide a steering angle sensor having an abnormality. An object of the present invention is to provide a steering angle detection device capable of accurately obtaining a steering angle with another steering angle sensor except for the above.

[0007]

According to a first aspect of the present invention, there is provided a steering angle detecting device for detecting a steering angle in a steering system of a vehicle. At least three steering angle sensors that output steering angle detection pulse signals having different phases according to the change,
It is characterized by comprising sensor abnormality detecting means for detecting abnormality of any of the steering angle sensors by detecting a change in the state of the steering angle detection pulse signal of each of the steering angle sensors.

According to the first aspect of the present invention, since there are at least three steering angle sensors and the phases of the steering angle detection pulse signals output from the respective steering angle sensors are different, it is possible to detect a change in these states. Accordingly, when any one of the steering angle detection pulses does not change state, it can be determined that an abnormality such as disconnection has occurred in the steering angle sensor system that has output the steering angle detection pulse.

The steering angle detecting device according to claim 2 is
The invention according to claim 1 is characterized in that one of the steering angle sensors also serves as a neutral position sensor for detecting a steering neutral position.

According to the second aspect of the present invention, both the steering angle and the steering neutral position can be detected by the steering angle sensor. Further, in the steering angle detecting device according to claim 3, in the invention according to claim 1, the sensor abnormality detecting means detects any state change at the time of rising or falling of each steering angle detection pulse signal. When no state change is detected in any one of the steering angle detection pulse signals, the steering angle sensor that outputs the corresponding steering angle detection pulse signal is determined to be abnormal.

According to the third aspect of the present invention, when a state change occurs in two of the three steering angle detection pulse signals, it can be determined that the steering wheel is being steered. In this state, when the state change has not occurred in the remaining one steering angle detection pulse signal, it can be accurately determined that the steering angle sensor outputting this signal is abnormal.

Further, in the steering angle detecting device according to a fourth aspect, in the invention according to the first aspect, the sensor abnormality detecting means is configured to change the state of any one of the rising and falling of each steering angle detection pulse signal. Is detected, and when a state change is not detected in any one of the steering angle detection pulse signals, the steering angle sensor that outputs the corresponding steering angle detection pulse signal is determined to be abnormal, and the remaining steering angle detection pulse signals are determined to be abnormal. It is characterized in that it is configured to calculate the steering angle based on this.

According to the fourth aspect of the present invention, since the steering angle is calculated by at least two steering angle sensors other than the steering angle sensor in which the abnormality has been detected, the calculation of the accurate steering angle can be continued.

[0014]

According to the first aspect of the present invention, since there are at least three steering angle sensors, and the phases of the steering angle detection pulse signals output from the respective steering angle sensors are different, these state changes can be prevented. By detecting, when a state change occurs in at least two steering angle detection pulse signals, it is possible to determine that a steering state has occurred, and in this state, when the remaining steering angle detection pulses do not change state, the steering operation is performed. It is possible to determine that an abnormality such as disconnection has occurred in the steering angle sensor system that has output the angle detection pulse, and it is possible to obtain an effect that the sensor abnormality can be accurately detected.

According to the second aspect of the present invention, one of the steering angle sensors also serves as the neutral position sensor for detecting the neutral position of the steering wheel, so that the number of parts is reduced and the cost is reduced. The effect that it can be obtained is obtained.

Further, according to the third aspect of the present invention, 2
The steering state of the steering wheel can be reliably detected by the state change of the two steering angle detection pulse signals,
When there is no change in the state of the remaining steering angle detection pulse signal, an effect is obtained that an abnormality in the steering angle sensor system that outputs the steering angle detection pulse signal can be accurately detected.

Further, according to the invention, when an abnormality of one of the steering angle sensor systems is detected, the steering angle is calculated based on the steering angle detection pulse signals of the remaining two steering angle sensors. Therefore, an effect that the calculation of the accurate steering angle can be continued even if the steering angle sensor abnormality occurs can be obtained.

[0018]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram showing an embodiment in which the present invention is applied to a rear wheel steering device. In the drawing, reference numeral 1 denotes a steering wheel. The steering gear 3 is connected to an AND pinion type steering gear 3.

The right end of the rack shaft of the steering gear 3 is connected to the front right wheel 6FR via a side rod 4R and a knuckle arm 5R, and the left end is a front wheel steering power cylinder 7
Is connected to the front left wheel 6FL via a side rod 4L and a knuckle arm 5L.

The front-wheel steering power cylinder 7 is driven by an engine via a hydraulic bridge circuit 8 in which left and right pressure chambers 7b and 7c defined by a piston 7a form a hydraulic pressure according to a steering torque attached to the steering shaft 2. Connected to a hydraulic pump 9 and a reservoir tank 10 driven by the

The hydraulic bridge circuit 8 has variable throttles 1R and 1 whose throttle areas continuously change according to the steering torque input to the steering wheel 1 in each of the four flow paths.
L, 2R, and 2L are inserted, and these variable diaphragms 1
A control valve that controls the hydraulic pressure supplied to the front wheel steering power cylinder 7 is configured by R, 1L, 2R, and 2L.

That is, the variable diaphragms 1R, 1L, 2R, 2
L depends on the magnitude of the input steering torque, in which, for example, two variable apertures 1L and 2L are linked by steering the steering wheel 1 to the left, and two variable apertures 1R and 2R are linked by rightward steering. The aperture area is configured to change in the direction of reduction.

On the other hand, the rear wheels 6RL, 6RR are also rotatably supported by knuckle arms 13L, 13R connected to the side rods 12L, 12R similarly to the front wheel steering system, and the inner ends of the side rods 12L, 12R. A tie rod 14 is connected therebetween, and a rear wheel steering actuator 15 is connected to the tie rod 14.

The rear-wheel steering actuator 15 includes a speed reduction mechanism 17 for converting the rotational force of the electric motor 16 into a moving direction of the tie rod 14, and a spring mechanism 18 for centering the tie rod 14.

The speed reduction mechanism 17 includes a drive gear (not shown) mounted on the output shaft of the electric motor 16 and the tie rod 1.
4 is provided with at least a ball nut screwed into a ball screw formed on the outer peripheral surface thereof and capable of rotating only, and a driven gear fixed coaxially to the ball nut and meshing with a driving gear.

A steering angle detecting mechanism 20 for detecting the rotation angle of the steering wheel 1, that is, the steering angle, is attached to the steering shaft 2. As shown in FIG. 2, the steering angle detection mechanism 20
, A first steering angle sensor 22A, a second steering angle sensor 22B, a third steering angle sensor 22C, and a neutral position. And a position sensor 24.

Here, the sensor disk 21 is provided with through holes 21a for detecting a steering angle at intervals of several degrees over the entire circumference on a concentric circle on the outer peripheral side, and concentrically, for example, 20 ° inside the sensor disk 21. Neutral position detection through hole 21 within a range of
b is drilled.

The first to third steering angle sensors 22A to 22A
22C and the neutral position sensor 24 are constituted by photointerrupters having a light emitting diode and a phototransistor opposed to each other with the sensor disk 21 interposed therebetween. Of these, the first to third steering angle sensors 22A to 22C are the sensor disks 21A to 22C. The neutral position sensor 24 is arranged in parallel so as to output steering angle detection pulse signals P1 to P3 having a phase difference of 60 ° by rotation of the sensor disc 21 at an arbitrary position facing the steering angle detection through hole 21a. When the steering wheel 1 is at a neutral position indicating a straight traveling state, the steering wheel 1 is disposed at a substantially central position in the circumferential direction of the neutral position detecting through hole 21b.

The electric motor 16 of the rear wheel steering actuator 15 is provided with a motor rotation angle sensor 25 composed of an encoder for outputting two pulse signals having a phase difference for detecting the rotation angle. Two pulse signals output from the rotation angle sensor 25 are input to a rotation angle measurement circuit 26, and the rotation angle measurement circuit 26 discriminates the rotation direction to form an addition pulse and a subtraction pulse. The current motor rotation angle θ _MP of the digital value is output by addition and subtraction.

The electric motor 16 constituting the rear wheel steering actuator 15 is controlled by a rear wheel steering controller 30.
Is driven and controlled. The rear wheel steering controller 30 includes a microcomputer having a built-in CPU, memory, and the like, and has a vehicle speed sensor 28 for detecting a vehicle speed on an input side thereof, and the three sets of steering angle sensors 22A to 22A.
C and a neutral position sensor 24, a rotation angle measurement circuit 26 for counting the value of a motor rotation angle sensor 25 provided on the output shaft of the electric motor 16 is connected, and a motor drive circuit 27 for driving the electric motor 16 is provided on the output side. It is connected.

The rear wheel steering controller 30
Any two of the steering angle sensors 22A to 22C
Detects steering direction and steering angle based on angle detection pulse signal
And, based on the detection signal of the neutral position sensor 24,
The neutral position is detected, and the steering angle and the vehicle speed of the vehicle speed sensor 28 are detected.
A predetermined calculation process is performed based on the detected value V and the rear wheel target
Steering angle θ_RTAnd calculate the rear wheel target steering angle θ._RTThe motor
Target rotation angle θ_MTAnd the motor target rotation angle θ_MTWhen
Current motor rotation angle θ from rotation angle measurement circuit 26 _MPBias with
Motor control signal SM and motor rotation direction signal according to difference ε
And SD to the motor drive circuit 27.

Next, an example of rear wheel steering control processing in which the operation of the above embodiment is executed by the rear wheel steering controller 30 will be described with reference to flowcharts of FIGS. The rear wheel steering control process of FIG. 3 is started as a main program when the key switch is turned on. First, in step S1, the current front wheel steering angle θ _F stored in the memory is read out. Next, the process proceeds to step S2 to read the vehicle speed detection value V of the vehicle speed sensor 28, and then proceeds to step S3 to perform rear wheel target steering based on the front wheel steering angle θ _F and the vehicle speed detection value V according to the following equation (1). The angle θ _RT is calculated.

Θ _RT = K · θ _F (1) K = (bLC _F C _R −aMC _F V ² ) / (aLC _F C _R)
-BMC _F V ²⁾ where, a is a front wheel and between the centers of gravity point distance, b is the rear wheels and between the centers of gravity point distance, L is the wheel base, C _F is the front wheel cornering power, C _R is the rear wheel cornering power, M is Vehicle mass.

As is apparent from the equation (1), the rear wheel target steering angle θ _RT is such that when the detected vehicle speed V is less than the predetermined vehicle speed, the steering direction of the rear wheels is improved so that the turning performance of the vehicle is improved. Becomes opposite to that of the front wheels, and when the vehicle speed detection value V exceeds a predetermined vehicle speed, the steering direction of the rear wheels is set to be the same as that of the front wheels so as to improve the running stability of the vehicle. .

[0035] Then, the process proceeds to step S4, the target rotation wheel target steering angle theta _RT and the electric motor 16 after being pre-stored based on memory, for example a wheel target steering angle theta _RT was calculated in step S3 The target motor rotation angle θ _MT of the electric motor 16 is calculated with reference to a storage table representing the relationship with the angle θ _M, and then the process proceeds to step S5, where the current motor rotation angle θ _MP stored in the memory is calculated. After reading, the process proceeds to step S6, in which the current motor rotation angle θ _MP is subtracted from the target motor rotation angle θ _MT to calculate a deviation ε between the two, and then proceeds to step S7.

In step S7, in order to perform the PID control, the target current value _IT is calculated by performing the operation of the following equation (2) based on the deviation ε, and the target current value IT is updated and stored in a predetermined storage area of the memory. I do.

I _T = [K ₁ + (1 / S) K ₂ + S · K ₃ ] ε (2) where K ₁ is a proportional gain, K ₂ is an integral gain, and K ₃ is a differential gain. , S are Laplace operators.

Next, the process shifts to step S8 to determine whether or not the vehicle is turned left. This determination is made by comparing the previous target motor rotation angle θ _MT (n-1) with the current target motor rotation angle θ _MT (n), and θ _MK (n)> θ _MT (n-1) , It is determined that the vehicle is turning left, and the process proceeds to step S9. The rotation direction signal SD is set to a logical value "1" representing left turning, and then the process proceeds to step S11, where θ _MK (n) ≦ θ _MT (n -1), it is determined that the vehicle is turning right, and the process proceeds to step S10.
After the turning direction signal SD is set to the logical value “0” representing the right turn, the process proceeds to step S11.

[0039] In step S11, the after driving control rear wheel actuator 15 outputs a motor control signal SM and the rotation direction signal SD of the current command value corresponding to the target current value I _T to a motor drive circuit 27 steps Return to S1.

Further, the rear wheel steering controller 30 executes the sensor abnormality detection processing of FIG. 4 every predetermined time (for example, 10 msc). In this sensor abnormality detection processing, first, in step S21, each of the steering angle detection pulse signals P1 to P3 is read, and then, the process proceeds to step S22, where the state of the first steering angle detection pulse signal P1 is a logical value "0". It is determined whether or not there is, and when the logical value is “0”, step S23 is performed.
To determine whether or not the previous value is the logical value “1”. If the previous value is the logical value “1”, the signal falls from the logical value “1” to the logical value “0”. It is determined that there is a change, and the routine goes to Step S24.

In step S24, the state change detection flag F1 is set to "1" indicating that a state change has occurred in which the first steering angle detection pulse signal P1 falls, and then the flow proceeds to step S25.

In step S25, step S21
Then, the state of each of the steering angle detection pulse signals P1 to P3 read in is updated and stored in the previous value storage area formed in the memory, and then the process proceeds to step S33.

On the other hand, if the result of the determination in step S22 is that the state of the first steering angle detection pulse signal P1 is a logical value "1", and if the result of the determination in step S23 is that the previous value is a logical value "0", The process proceeds to S26 and the second
It is determined whether or not the state of the steering angle detection pulse signal P2 is a logical value “0”. If the state is a logical value “0”, the process proceeds to step S27 to determine whether the previous value is a logical value “1”. If the previous value is the logical value "1", it is determined that the signal has changed to a falling state, and step S28 is performed.
Move to

In step S28, the state change detection flag F2 is set to "1" indicating that a state change in which the signal falls to the second steering angle detection pulse signal P2, and then the flow proceeds to step S25. .

When the result of the determination in step S26 is that the state of the second steering angle detection pulse signal P2 is a logical value "1", and when the result of the determination in step S27 is that the previous value is a logical value "0", the step Proceed to S30 for the third
It is determined whether the state of the steering angle detection pulse signal P3 is a logical value “0”. If the state is a logical value “0”, the process proceeds to step S31 to determine whether the previous value is a logical value “1”. If the previous value is the logical value "0", the process directly proceeds to the step S25, and if the previous value is the logical value "1", it is determined that the signal has fallen and the state changes to the step S32. Move to

In step S32, the state change detection flag F3 is set to "1" indicating that a state change in which the signal falls to the third steering angle detection pulse signal P3, and then the flow proceeds to step S25. .

Further, the determination result of step S30 is the third
If the steering angle detection pulse signal P3 of this example is a logical value "1", the process directly proceeds to step S25. In step S33, increments the elapsed time T _R to reset the state change detection flag F1~F3 every predetermined time, and then proceeds to step S34, the elapsed time T _R in advance at least a first, second and third steering Angle detection pulse signal P1
~P3 it is determined whether exceeds the set time T _X which is set to more than the time to round, and returns to the main program as it terminates the timer interruption process when a _{T R ≦ T X, T R} > _If it is Tx, the process moves to step S35.

In step S35, it is determined whether or not a state change detection flag F1 corresponding to the first steering angle detection pulse signal P1 is set to "1". The process proceeds to step S36 to determine whether or not the state change detection flag F3 corresponding to the third steering angle detection pulse signal P3 is set to "1". In S37, it is determined whether or not the state change detection flag F2 corresponding to the second steering angle detection pulse signal P2 has been set to "1". Steering angle sensors 22A to 22C
Is normal, and the process shifts to step S38.

In step S38, the steering angle sensor 2
The steering angle detection pulse signals P1 and P2 of 2A and 22B are selected, and Pi = P1 and Pj = P2 are selected. Then, the process proceeds to step S39 to change the state change detection flags F1 to F2.
3 is reset to "0", and then step S40
To end the timer interrupt processing is cleared to "0" the transition to the elapsed time T _R To return to the main program.

If the result of the determination in step S37 is that the state change detection flag F2 has been reset to "0", it is determined that the steering angle sensor 22B is in an abnormal state, and the flow proceeds to step S41. Steering angle detection pulse signals P1 and P3 of the two steering angle sensors 22A and 22C.
Is selected, and Pi = P1 and Pj = P3 are selected, and the routine goes to the step S39.

Further, if the result of the determination in step S36 is that the state change detection flag F3 has been reset to "0", the flow proceeds to step S42, and the state change detection flag F2 is set to "1" as in step S37. It is determined whether or not the third steering angle sensor 22C is in an abnormal state when it is set to "1", and the process proceeds to step S38, where "0" is set.
If the steering angle has been reset, it is determined that there is no change in the steering angle, and the routine goes to step S39.

Further, when the result of the determination in step S35 is that the state change detection flag F1 has been reset to "0", the flow shifts to step S43 to determine whether or not the state change detection flag F3 has been set to "1". If it is reset to "0", it is determined that there is no change in the steering angle, and the process directly proceeds to step S39. If it is set to "1", the process proceeds to step S4.
Move to 4.

In this step S44, it is determined whether or not the state change detection flag F2 is set to "1".
If this is reset to "0", it is determined that there is no change in the steering angle, and the process directly proceeds to step S39. If it is set to "1", the steering angle sensor 2
It is determined that 2A is in an abnormal state, and the process proceeds to step S45.

In step S45, the steering angle sensor 2
After selecting the steering angle detection pulse signals P2 and P3 of 2B and 22C and selecting Pi = P2 and Pj = P3, the process proceeds to step S39.

Further, the rear wheel steering controller 30 includes:
The steering angle calculation processing of FIG. 5 is executed every predetermined time (for example, 10 msc). In the steering angle calculation process of FIG. 5, first, in step S51, the two steering angle detection pulse signals Pi and Pj selected in the sensor abnormality detection process of FIG. 4 are read, and then the process proceeds to step S52, where It is determined whether or not the steering angle detection pulse signal Pi has a logical value “0”, and if the signal has a logical value “0”, the process proceeds to step S53.

In step S53, it is determined whether or not the previous value of the steering angle detection pulse signal Pi stored in the memory is a logical value "1". If the previous value is a logical value "0", a state change occurs. If the logical value is "1", it is determined that a change in the state of the signal falling has occurred, and the process proceeds to step S54.

In this step S54, it is determined whether or not the other steering angle detection pulse signal Pj has the logical value "1". If the logical value is "1", it is determined that the vehicle is in a left turning state, and the process proceeds to step S55. Then, the count value of the counter representing the steering angle detection value θ _D formed in the memory is incremented by “1”, and then the process proceeds to step S56, where the state of the steering angle detection pulse signal Pi is stored in the memory in the previous time. After updating and storing the value in the value storage area, the timer interrupt processing ends and the program returns to the main program.

If the result of the determination in step S53 is that the previous value is a logical value "0", and if the result of the determination in step S54 is that the other steering angle detection pulse signal Pj is a logical value "0", the aforementioned step S56 is directly performed. Move to

On the other hand, when the result of the determination in step S52 is that the steering angle detection pulse signal Pi is a logical value "1", the flow proceeds to step S57, where the previous value is a logical value "0".
It is determined whether the logical value is "1". If the logical value is "1", the process directly proceeds to step S56. If the logical value is "0", it is determined that the signal is rising, and step S5 is performed.
Move to 8.

In step S58, it is determined whether or not the other steering angle detection pulse signal Pj has a logical value "1".
When this is the logical value "0", the step S
If the logical value is "1", it is determined that the vehicle is turning right, and the process proceeds to step S59, where the count value of the counter formed as described above is counted down by "1". The process moves to S56.

Further, the rear wheel steering controller 30
Executes the front wheel steering angle calculation processing of FIG. 6 every predetermined time (for example, 10 msec). This front wheel steering angle calculation processing
First, in step S61, the moving average value θ _CA as the pseudo-neutral position and the value θ _C of the original neutral position, which are calculated in the previous interrupt cycle and stored in the predetermined storage area of the memory, are read, and then the process proceeds to step S62. It reads the steering angle theta _D set by the steering angle computing process in FIG. 5 and.

Then, the flow shifts to step S63, in which the moving average value θ _CA is calculated by performing the operation of the following equation (4), and this is updated and stored in the moving average value storage area of the memory. θ _CA = θ _CA −θ _C / 100 + θ _D / 100 (4) The calculation in step S63 corresponds to obtaining a moving average of 100 steering angles.

Next, the process proceeds to step S64 to determine whether or not the neutral position detection signal PN of the neutral position sensor 24 is "1".
When it is determined that the steering wheel 1 is in the substantially neutral position indicating the straight running state and the moving average value θ _CA calculated in step S63 accurately indicates the neutral position, the process proceeds to step S65. Then, the moving average value θ _CA is updated and stored in the predetermined storage area of the memory as the neutral position θ _C , and the process proceeds to step S66.

On the other hand, when the result of the determination in step S64 is that the neutral position signal PN is a logical value "0", it is determined that the steering wheel 1 is not at the neutral position, and the neutral position stored in the predetermined storage area of the memory is determined. Directly to step S66 without updating.

[0065] At step S66, the front-wheel steering the moving average value theta _CA and a value obtained by subtracting the neutral position theta _C stored from the read steering angle theta _D to the neutral position storage area of the memory in step S62 is calculated at step S63 The angle θ _F is updated and stored in the front wheel steering angle storage area of the memory, the processing is terminated, and the processing returns to the predetermined main program.

Here, when the front wheel steering angle θ _F is positive, it indicates that the wheel is turned right, and when the value is negative, it indicates that the wheel is turned left. Therefore, at the time of the previous steering of the vehicle, the respective steering angle detection pulse signals P1 to P3 are normal, Pi = P1, Pj = P2 are set, and the neutral position θ _C according to the straight traveling state is set. It is assumed that the vehicle is traveling straight in a non-steering state in which the steering wheel 1 is in the neutral position. In this straight traveling state, for example, as shown at time t ₀ in FIG.
Assuming that the first steering angle detection pulse signal P1 and the second steering angle detection pulse signal P2 have a logical value “1” and the third steering angle detection pulse signal P3 has a logical value “0”.
Since there is no state change in these steering angle detection pulse signals P1 to P3, when the sensor abnormality detection processing in FIG. 4 is executed, steps S21, S22, S26, S30 and S30 are performed.
Then, the process proceeds to step S25 via step 31, and the state change detection flags F1 to F3 are all maintained at "0".

[0067] Reset Therefore, when the elapsed time T _R becomes state exceeding the set value T _X is incremented, the process proceeds from step S34 to step S35, the state change detecting flag F1~F3 is "0" It is determined that the vehicle is not in the steering state in step S43, and the flow advances to step S39 to change the state change detection flags F1 to F3.
The F3 is reset to "0", will be cleared to "0" the elapsed time T _R, has been set at the time of the previous steering Pi =
P1 and Pj = P2 are maintained.

Therefore, when the steering angle calculation process of FIG. 5 is executed, the first and second steering angle detection pulse signals P1 and P2 do not change to a falling state, so that the count value of the counter is used. Steering angle detection value θ _D
Maintain a state substantially equal to the neutral position θ _C.

When the front wheel steering angle calculation processing of FIG. 6 is executed, since the detected steering angle θ _D is substantially equal to the neutral position θ _C , the moving average value θ _CA calculated in step S63 does not change. since further the neutral position detection signal PN neutral position sensor 24 becomes the logic "1", the moving average value theta _CA is set as the neutral position theta _C, a neutral position theta _C from the steering angle detection value theta _D front-wheel steering angle θ _F which is obtained by subtracting is substantially equal to zero.

[0070] Accordingly, when the wheel steering control process after 3 has been executed, is wheel target steering angle theta _RT after being calculated substantially becomes zero, the target current I _T also zero for the electric motor 16 Thus, the electric motor 16 is stopped.

When the steering wheel 1 is turned right from the straight running state to the right turning state, when all the steering angle sensors 22A to 22C are normal, the steering angle sensor 22A is turned on according to the left turning of the steering wheel 1. ~
As shown in FIG. 7, first to third steering angle detection pulse signals P1 to P3 each having a phase difference of 60 ° are output from 22C.

[0072] Then, step S24 through first the steering angle detection pulse signal P1 falls at time t ₁ in FIG. 7, a step S43 from step S42 when the subsequent sensor abnormality detecting process of FIG. 4 is executed The state change detection flag F1 is set to "1", and the current state of each of the steering angle detection pulse signals P1, P2 and P3, that is, P1 = "0", P2 = "1" and P3 = “1” is updated and stored in the previous value storage area.

[0073] Once this point t _1, assumed to be cleared to the elapsed time T _R is for example "0", step S3
Although the elapsed time 3 T _R becomes T _R = 1 is incremented, because a set value T _X smaller value, returns to the main program as it ends the timer interrupt process.

[0074] Then, since the up time t ₂ does not cause a state change in the steering angle detection pulse signal P1 to P3, the step when the process of FIG. 4 is executed S21 to S23, S2
6, S30, proceeds to step S33 through step S25, it is repeated to end the timer interrupt process is incremented elapsed time T _R through step S34.

Then, at time t ₂ , as shown in FIG.
When the steering angle detection pulse signal P2 of FIG. 4 falls, similarly, when the processing of FIG. 4 is executed, the processing shifts to step S48 via steps S26 and S27, and the state change detection flag F2
Is set to "1".

[0076] Since this elapsed time T _R, even when the set value T _X smaller value, as it ends the timer interrupt process. Thereafter, the third steering angle detection pulse signal when P3 falls of 7 at time t _3, the process proceeds to step S32 through steps S30, S31 when the processing of FIG. 4 is executed, the state change The detection flag F3 is set to "1".

[0077] Since this elapsed time T _R, even when the set value T _X smaller value, as it ends the timer interrupt process. Thereafter, when the elapsed time T _R at time t ₄ is a state exceeding the set value T _X, in the process of FIG. 4, step S
Then, the process proceeds from step S35 to step S35, where all of the state change detection flags F1 to F3 are set to "1". Therefore, it is determined that each of the steering angle sensors 22A to 22C is normal, and steps S36 and S37 are performed. Shift to S38,
When the steering angle sensors 22A and 22B are selected, Pi = P1,
Pj = set to P2, then resets to migrate each state change detection flag F1~F3 to "0" in step S39, the timer split is cleared to "0" to the elapsed time T _R at step S40 End processing.

For this reason, when the steering angle calculation processing of FIG. 5 is executed, the calculation based on the first and second steering angle detection pulse signals P1 and P2 is performed as in the straight steering state.
Immediately after the time point t _{1 in} FIG. 7, when the processing in FIG. 5 is executed,
In steps S52 and S53, the falling state change of the first steering angle detection pulse signal P1 is detected, and the second
Since the steering angle detection pulse signal P2 is logic value "1", the process proceeds to step S55, by counting up the count value of the counter, the steering angle detection value theta _D is incremented, according to this figure The front wheel steering angle θ _F calculated in 6 is increased in the forward direction so as to indicate a right turn.

By increasing the front wheel steering angle θ _F , FIG.
In wheel steering control process after the rear wheel target steering angle theta _RT is calculated based on the front-wheel steering angle theta _F and the vehicle speed detection value V, when the motor current I _T corresponding thereto is calculated, the direction of rotation signal The SD and the motor control signal SM are output to the motor drive circuit 27, and the electric motor 16 is driven, for example, to perform normal rotation to perform suitable rear wheel steering control.

When the steering wheel 1 is turned left from the straight running state to the left turning state, the steering angle detection pulse signals P1 to P3 are set as shown in FIG.
Contrary to the above-mentioned right turning state, the phase is delayed by 60 ° from the third steering angle detection pulse signal P3 toward the first steering angle detection pulse signal P1.

[0081] When the state change in which the first steering angle detection pulse signal P1 at time t ₁₁ rises to the logical value "1" from a logical value "0" occurs, when the process of FIG. 5 is executed immediately after the Then, the process proceeds from step S52 to step S57, and since the previous value is the logical value “0”, the process proceeds to step S58.
Proceeds to, the second steering angle detection pulse signal P2 is logic value "1" and proceeds to step S59 it is determined that the left turn, is decremented steering angle detection value theta _D by counting down the counter, In response to this, the front wheel steering angle θ _F calculated in FIG. 6 is increased in the negative direction so as to indicate a left turn.

The increase in the front wheel steering angle θ _{F in} the negative direction causes the front wheel steering angle θ _F in the rear wheel steering control processing of FIG.
A rear wheel target steering angle theta _RT is calculated on the basis of the _F and the vehicle speed detection value V, when the motor current I _T is calculated in accordance with this, the rotation direction signal SD and the motor control signal SM is the motor drive circuit 27 The output is output and the electric motor 16 is driven to rotate in the reverse direction to perform suitable rear wheel steering control.

However, in the above-described right-turning state, as shown in FIG.
_When an abnormality such as disconnection occurs at ₂₁ and the second steering angle detection pulse signal P2 is fixed to the state of the logical value "0",
When the sensor abnormality detecting process of FIG. 4 is executed, for example, over the elapsed time T _R at time t ₂₂ is the set value T _X, and proceeds from step S34 to step S35, at this time in each state change detection flag F1~ Since F3 is set to "1", it is determined that each of the steering angle sensors 22A to 22C is normal, and the first and second steering angle detection pulse signals P
After 1 and P2 are selected for calculating the steering angle, the state change detection flags F1 to F3 are reset to "0".

Therefore, in the next abnormality detection cycle, the time t
Since they produce the first steering angle detection pulse signal P1 is lowered state change standing at _23, although the state change detection flag F1 is set to "1", originally time for the second steering angle detection pulse signal P2 t ₂₄ point in it is caused to fall state change, because it is fixed to the logic value "0", without causing a state change, the state change detection flag F2 is the elapsed time T _R exceeds the set value T _X maintaining the state of being reset until t ₂₆ "0", further third since they produce falling state change at time t ₂₅ for steering angle detection pulse signal P3, the state change detection flag F3 is set to "1" Is done.

[0085] Therefore, when the elapsed time T _R at time t ₂₆ exceeds the set value T _X, and proceeds from step S34 to step S35, and the state change detection flag F1 is set to "1", step The flow shifts to S36, where the state detection flag F3 is also set to "1", and the flow shifts to step S37. However, since the state detection flag F2 remains reset to "0", the second steering angle sensor 2
2B is determined to be in an abnormal state, and step S41 is performed.
And the second steering angle sensor 22B in the abnormal state
Except for the normal first and third steering angle detection pulse signals P1
And P3 are selected and set as Pi = P1, Pj = P3.

For this reason, when the steering angle calculation processing of FIG. 5 is executed, the steering angle detection value θ _D is calculated based on the normal first and third steering angle detection pulse signals P 1 and P 3, and is accurately calculated. it is possible to calculate the Do steering angle detection value theta _D, also becomes accurate value the front-wheel steering angle theta _F calculated in Figure 6, Figure 3
Rear wheel steering control processing can be suitably continued, and good running stability can be ensured.

Incidentally, when the steering angle calculation processing of FIG. 5 is executed based on the normal first steering angle detection pulse signal P1 and the abnormal second steering angle detection pulse signal P2,
Since the second steering angle detection pulse signal P2 maintains the state of the logical value "0" at any time of the rising state change and the falling state change of the first steering angle detection pulse signal P1, step S55 and step S55 are performed. The process directly goes to step S56 without going to S59,
Steering angle detection value theta _D made by the count value of the counter becomes possible to maintain a constant value irrespective of the steering of the steering wheel 1, will be caused a large deviation from the actual steering angle, the rear wheels of Fig. 3 The steering control process cannot be suitably executed.

When the first steering angle sensor 22A is in an abnormal state such as a disconnection and the first steering angle detection pulse signal P1 is fixed to the logical value "0", the state shown in FIG.
Since the state change detection flag F1 alone is reset to “0” in the sensor abnormality detection processing of “1” and the remaining state change detection flags F2 and F3 are set to “1”,
When the elapsed time T _R exceeds the set value T _X, step S
35, the process proceeds to step S43, and then proceeds to step S45 via step S44, where normal second and third steering angle detection pulse signals P2 and P3 are selected, and Pi = P
2, Pj = P3, so that normal steering angle calculation processing and rear wheel steering control processing can be performed.

Similarly, when the third steering angle sensor 22C is in an abnormal state such as elasticity, the third steering angle detection pulse signal P3
Is fixed to the logical value "0", the state where only the state change detection flag F3 is reset to "0" in the sensor abnormality detection processing of FIG. 4 is continued, and the remaining state change detection flag F1 and since F2 is set to "1", when the elapsed time T _R exceeds the set value T _X, and proceeds from step S35 to step S36, step S42
Then, the process proceeds to step S38, and the normal first and second
Of the steering angle detection pulse signals P1 and P2 are selected, and Pi
= P1, Pj = P2, so that normal steering angle calculation processing and rear wheel steering control processing can be performed.

In the above embodiment, the steering angle detecting through hole 2 of the sensor disk 21 of the steering angle detecting mechanism 20 is used.
1a to the first to third steering angle sensors 22A to 22C
Are described, but the present invention is not limited to this. As shown in FIG. 10, three sets of steering angle detection through holes whose phases in the circumferential direction are shifted by 60 ° in the sensor disk 21 are shown. By providing the concentric circles 41a to 41c and arranging the first to third steering angle sensors 22A to 22C so as to face each of them, the same steering angle detection pulse signals P1 to P3 as in FIGS. You can also get

Further, as shown in FIG. 11, a steering angle detecting through hole 72 corresponding to the steering angle detecting through hole 21a is formed concentrically with the neutral position detecting through hole 21b of the sensor disk 21 of FIG. And the neutral position signal P of the neutral position sensor 24
N can be used as the third steering angle detection pulse signal P3. In this case, as shown in FIG. 12, the neutral position signal PN is a neutral position detection through-hole at the neutral position of the steering wheel 1 as shown in FIG. since the wide pulse corresponding to 21b, in order to avoid determining that the abnormality when the wide pulse arrives, the wide pulse setting value T _X of the elapsed time T _R of the sensor abnormality detecting process of FIG. 4 It is preferable to set the time sufficiently long so that the change in the rising state and the change in the falling state can be detected. In this case, the neutral position sensor 24 can be shared for detecting the steering angle, so that the number of sensors can be reduced and the cost can be reduced.

Further, in the above embodiment, the case where the falling state changes of the first to third steering angle detection pulse signals P1 to P3 are detected in order to detect the sensor abnormality has been described, but the present invention is not limited to this. Instead, a change in the rising state may be detected.
You may make it detect both the rise and fall state changes.

Further, in the above embodiment, the first to the first
The case where the phase differences of the third steering angle detection pulse signals P1 to P3 are all equal has been described. However, the present invention is not limited to this. All the phase differences can be different, and any phase difference can be set. Can be.

Further, in the above-described embodiment, the case where the detected steering angle θ _D is calculated by the calculation processing of FIG. 5 has been described. However, the present invention is not limited to this. It may be calculated, or may be calculated by a logic circuit.

Further, in the above-described embodiment, a case has been described where a transmission type optical sensor using a steering angle detection through hole is applied as a steering angle sensor. However, the present invention is not limited to this, and a reflection type optical sensor is applied. In addition, a non-contact sensor such as a sensor that magnetically detects a steering angle, such as a Hall element, is not limited to an optical sensor.

[0096] In the above embodiment has described the case of correcting the neutral position by providing a neutral position sensor 24, and this is omitted, the neutral moving average on the moving average of the steering angle detection value theta _D You may make it set as a position.

Further, in the above embodiment, the case where three steering angle sensors 22A to 22C are provided has been described. However, the present invention is not limited to this, and four or more steering angle sensors may be provided. Is also good.

Further, in the above-described embodiment, the case where the present invention is applied to the rear wheel steering control device has been described. However, the present invention is not limited to this, and electric power steering for electric vehicles and other steering systems are applicable. It can be applied to devices that use corners.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a first embodiment of the present invention.

FIG. 2 is a configuration diagram illustrating an example of a steering angle detection mechanism.

FIG. 3 is a flowchart illustrating an example of a rear wheel steering control processing procedure of a rear wheel steering controller.

FIG. 4 is a flowchart illustrating an example of a sensor abnormality detection processing procedure of a rear wheel steering controller.

FIG. 5 is a flowchart illustrating an example of a steering angle detection processing procedure of a rear wheel steering controller.

FIG. 6 is a flowchart illustrating an example of a front wheel steering angle calculation processing procedure of a rear wheel steering controller.

FIG. 7 is a waveform diagram showing first to third steering angle detection pulse signals in a right turn state.

FIG. 8 is a waveform diagram showing first to third steering angle detection pulse signals in a left turning state.

FIG. 9 is a waveform diagram showing first to third steering angle detection pulse signals when a disconnection abnormality has occurred in a second steering angle sensor.

FIG. 10 is a schematic configuration diagram showing a modification of the steering angle detection mechanism.

FIG. 11 is a schematic configuration diagram showing still another modified example of the steering angle detection mechanism.

FIG. 12 is a waveform chart showing first to third steering angle detection pulse signals in FIG. 11;

[Explanation of symbols]

 Reference Signs List 1 steering wheel 2 steering shaft 6FL, 6FR front wheel 6RL, 6RR rear wheel 15 rear wheel side actuator 16 electric motor 20 steering angle detecting mechanism 21 vehicle speed sensor 22A first steering angle sensor 22B second steering angle sensor 22C third steering Angle sensor 24 Neutral position sensor 26 Rotation angle measurement circuit 27 Motor drive circuit 30 Controller for rear wheel steering

Claims (4)

[Claims] 1. A steering angle detecting device for detecting a steering angle in a steering system of a vehicle, comprising: at least three steering angle sensors for outputting steering angle detection pulse signals having different phases according to a change in the steering angle of the steering system. And a sensor abnormality detecting means for detecting an abnormality of any of the steering angle sensors by detecting a change in the state of the steering angle detection pulse signal of each of the steering angle sensors. 2. The steering angle detecting device according to claim 1, wherein one of the steering angle sensors also serves as a neutral position sensor for detecting a neutral steering position. 3. The sensor abnormality detecting means detects a state change at the time of rising or falling of each steering angle detection pulse signal, and no state change is detected at any one of the steering angle detection pulse signals. 2. The steering angle detection device according to claim 1, wherein the steering angle sensor that outputs a corresponding steering angle detection pulse signal is determined to be abnormal. 4. The sensor abnormality detecting means detects a state change at the time of rising or falling of each steering angle detection pulse signal, and no state change is detected at any one of the steering angle detection pulse signals. The steering angle sensor that outputs a corresponding steering angle detection pulse signal is determined to be abnormal, and the steering angle is calculated based on the remaining steering angle detection pulse signal. Item 1
The steering angle detection device according to any one of the preceding claims.