JP3509465B2 - Steering angle detector - Google Patents

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, an auxiliary steering device for assisting steering of at least one of front wheels and rear wheels in response to steering of the steering system. The present invention relates to a steering angle detection device suitable for application to an active suspension and the like.

[0002]

2. Description of the Related Art As a conventional steering angle detecting device, for example, there is one described in Japanese Patent Laid-Open No. 2-299976 (hereinafter, simply referred to as a conventional example).

In this conventional example, a disk-shaped sensor disk fixed to the steering shaft, and a first sensor section and a second sensor section which are fixed to the vehicle body side and are composed of a light emitting diode and a photo IC are provided. It has a steering wheel angle sensor and a steering wheel neutral position detection sensor having the same configuration, and the sensor disk is provided with steering angle detection slits at intervals of several degrees over the entire circumference,
A neutral position detecting slit is opened inside the steering angle detecting slit in a range of, for example, 20 °, and the first sensor portion and the second sensor portion have a half pitch interval corresponding to the steering angle detecting slit of the sensor disk. Since the steering wheel steering angle sensor has a phase of 90 degrees as shown in FIG.
By outputting the first and second rectangular pulse signals P1 and P2 which are deviated from each other and counting the rectangular pulse signals to detect the steering angle, the neutral position detecting sensor detects the presence or absence of the neutral position detecting slit. A steering angle detecting device for detecting a neutral position is described.

With regard to the steering wheel neutral position detection sensor, the steering angle detection value of the steering wheel steering angle sensor when the steering wheel neutral angle detection sensor reaches one end of the neutral position detection slit and is turned on in the state where the steering wheel is steered in the same direction. It is normal when the value obtained by subtracting the steering angle detection value of the steering wheel steering angle sensor when reaching the other end and being in the off state is within the allowable range of the angle of the neutral position detection slit plus the allowable value. If it is outside the allowable range, it is determined to be abnormal.

[0005]

However, in the above-mentioned conventional steering angle detecting device, the first sensor portion and the second sensor portion are provided.
By outputting the first and second rectangular pulse signals P1 and P2 which are 90 ° out of phase from the sensor unit, the steering direction and the steering angle can be determined based on the first and second rectangular pulse signals P1 and P2. Although it can be detected, when a short circuit occurs between the first sensor unit and the second sensor unit, it becomes a wired AND, and as shown in FIG. 11, the first and second rectangular pulses are generated. The signals P1 and P2 are
In the state shown in FIG. 10, the pulse width is half the pulse width in the on-state and the same phase in the on-state, and the pulse waveform is output for the time being. Cannot be detected and a pulse signal having a period smaller than that of the first and second rectangular pulse signals P1 and P2 cannot be detected. Therefore, another pulse signal such as a steering wheel neutral position sensor is used to cause an abnormality. There is an unsolved problem that the determination cannot be performed and the first sensor unit and the second sensor unit have to be determined to be normal.

Therefore, the steering angle calculated by using the first and second rectangular pulse signals of the same phase monotonically increases with respect to the state before the occurrence of the short circuit abnormality. The value deviates from the actual steering angle.

Therefore, the present invention has been made by paying attention to the unsolved problem of the above-mentioned conventional example, in which at least two steering angle sensors have a short circuit abnormality or the like, and pulse signals of the same phase or close to this are generated. An object of the present invention is to provide a steering angle detection device that can accurately detect a sensor abnormality when it is in an output state.

[0008]

In order to achieve the above object, a steering angle detecting device according to a first aspect of the present invention is a steering angle detecting device for detecting a steering angle in a steering system of a vehicle. A plurality of steering angle sensors that output steering angle detection pulse signals having different phases according to changes, a phase difference detection unit that detects a phase difference between the steering angle detection pulse signals of the plurality of steering angle sensors, and the phase difference detection And a sensor abnormality detecting means for determining that the steering angle sensor has a short circuit abnormality when the phase difference detected by the means is less than a set value.

According to the first aspect of the present invention, the phase difference between the steering angle detection pulse signals output from the plurality of steering angle sensors is detected by the phase difference detecting means, and the detected phase difference becomes less than the set value. to the sensor abnormality detecting means, short circuit abnormality is determined to have occurred between the two sensors.

A steering angle detecting device according to a second aspect of the present invention is
In the invention according to claim 1, the phase difference detecting means is
It is characterized in that a value obtained by subtracting a change time of a steering angle detection pulse signal of another steering angle sensor from a change time of a steering angle detection pulse signal of one steering angle sensor is detected as a phase difference. .

According to the second aspect of the present invention, the change times of the steering angle detection pulse signals of the plurality of steering angle sensors are individually detected and the change time difference between the steering angle sensors is obtained.
It is possible to determine that the phase difference is smaller as the change time difference is smaller.

Further, in the steering angle detecting device according to a third aspect of the present invention, in the invention according to the first aspect, the phase difference detecting means is configured such that the steering angle detecting pulse signal of one steering angle sensor changes from another steering angle to another steering angle. It is characterized in that the measuring time until the steering angle detection pulse signal of the sensor changes is detected as a phase difference.

According to the third aspect of the invention, the time from the time when the steering angle detection pulse signal of one steering angle sensor changes to the time when the other steering angle sensors change among the plurality of steering angle sensors is measured. It is possible to determine that the phase difference is smaller as the measurement time is shorter.

[0014]

According to the invention of claim 1, the phase difference detecting means detects the phase difference of the steering angle detection pulse signals of the plurality of steering angle sensors, and the sensor abnormality detecting means detects the phase difference is less than the set value. since so as to detect that it is a short-circuit malfunction of the sensor when it is, in the short-circuit abnormality between the steering angle sensor
Even if the phase difference between the steering angle detection pulse signals in the plurality of steering angle sensors is small, it is possible to reliably detect the sensor abnormality.

According to the second aspect of the present invention, the phase difference detecting means has the change time of the steering angle detection pulse signal at one steering angle sensor and the change time of the steering angle detection pulse signal at another steering angle sensor. It is possible to determine the magnitude of the phase difference from this change time difference, and it is possible to accurately detect the phase difference of the steering angle detection pulse signals in the plurality of steering angle sensors. The effect of being able to be obtained is obtained.

Further, according to the invention of claim 3, the phase difference detecting means changes from the time when the steering angle detection pulse signal of one steering angle sensor changes to the time when the steering angle detection pulse signal of another steering angle sensor changes. Since the elapsed time of is measured, the magnitude of the phase difference can be determined from this elapsed time, and the effect that the phase difference of the steering angle detection pulse signals in the plurality of steering angle sensors can be accurately detected is obtained. To be

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION 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 system. In the figure, 1 is a steering wheel, and the steering wheel 1 is a rack via a steering shaft 2. It 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 the side rod 4R and the knuckle arm 5R, and the left end thereof is the power cylinder 7 for steering the front wheel.
Is connected to the front left wheel 6FL via the side rod 4L and the knuckle arm 5L.

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

The hydraulic bridge circuit 8 has variable throttles 1R, 1 whose throttle areas continuously change according to steering torque input to the steering wheel 1 in each of the four flow paths.
L, 2R, 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
For L, for example, two variable apertures 1L and 2L are interlocked by steering the steering wheel 1 to the left, and two variable apertures 1R and 2R are interlocked by steering to the right, respectively, depending on the magnitude of the steering torque input. 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 are rotatably supported. A tie rod 14 is connected in between, and a rear wheel steering actuator 15 is connected to this tie rod 14.

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

The 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 includes at least a ball nut that is screwed into a ball screw formed on the outer peripheral surface and is only rotatable, and a driven gear that is coaxially fixed to the ball nut and meshes with a drive 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 includes a steering shaft 2
A disk-shaped sensor disc 21 fixed to the first disc, and a first steering angle sensor 22, a second steering angle sensor 23, and a neutral position sensor 2 which are arranged so as to face the sensor disc 21.
It is composed of 4 and.

Here, the sensor disk 21 has through holes 21 for detecting the steering angle on the outer peripheral side thereof at intervals of several degrees over the entire circumference.
A is provided, and a neutral position detecting through hole 21b is provided concentrically inside the a in a range of about 20 °.

The first steering angle sensor 22, the second steering angle sensor 23, and the neutral position sensor 24 are photointerrupters each having a light emitting diode and a phototransistor that face each other with the sensor disk 21 in between. Among them, the first steering angle sensor 22 and the second steering angle sensor 23 are arranged side by side at a pitch half the width of the through hole 21a at an arbitrary position facing the steering angle detecting through hole 21a of the sensor disk 21, The neutral position sensor 24 is arranged at a substantially central position in the circumferential direction of the neutral position detecting through hole 21b when the steering wheel 1 is in a neutral position indicating a straight traveling state.

Further, 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 thereof. The two pulse signals output from the rotation angle sensor 25 are input to the rotation angle measurement circuit 26, the rotation angle measurement circuit 26 discriminates the rotation direction to form an addition pulse and a subtraction pulse, and these are added by an up / down counter. Adds and subtracts and outputs the current motor rotation angle θ _MP as a digital value.

The electric motor 16 constituting the rear wheel steering actuator 15 is connected to the rear wheel steering controller 30.
Is controlled by. The rear wheel steering controller 30 is configured to include a microcomputer having a CPU, a memory and the like built therein, and a vehicle speed sensor 28 for detecting a vehicle speed on the input side thereof, the two sets of steering angle sensors 22 and 23, and a neutral position. The sensor 24 and a motor rotation angle sensor 25 provided on the output shaft of the electric motor 16 are connected, and the output side is connected to a motor drive circuit 27 that drives the electric motor 16.

Then, the rear wheel steering controller 30 is
The steering direction and the steering angle are detected based on the steering angle detection pulse signals of the steering angle sensors 22 and 23, the neutral position is detected based on the detection signal of the neutral position sensor 24, and the steering angle and the vehicle speed of the vehicle speed sensor 28 are detected. based on the detected value V to calculate the rear wheel target steering angle theta _RT performs predetermined arithmetic processing, and thereafter the wheel target steering angle theta _RT into a target motor rotational angle theta _MT, the motor target rotation angle theta _The motor control signal SM and the motor rotation direction signal SD corresponding to the deviation ε between the _MT and the current motor rotation angle θ _MP from the rotation angle measurement circuit 26 are output to the motor drive circuit 27.

Next, the operation of the above embodiment will be described with reference to the flowcharts of FIGS. 3 to 5 showing an example of the rear wheel steering control processing executed by the rear wheel steering controller 30. 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, Next, in step S2, the vehicle speed detection value V of the vehicle speed sensor 28 is read, and then in step S3, the rear wheel target steering is performed based on the front wheel steering angle θ _F and the vehicle speed detection value V according to the following equation (1). Calculate the angle θ _RT .

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 the distance between the front wheels and the center of gravity, b is the distance between the rear wheels and the center of gravity, L is the wheel base, C _F is the front cornering power, C _R is the rear cornering power, and M is Vehicle mass.

As is clear from the equation (1), the rear wheel target steering angle θ _RT is the steering direction of the rear wheels so that the turning performance of the vehicle is improved when the detected vehicle speed V is less than the predetermined vehicle speed. Is in the opposite direction to that of the front wheels, and when the vehicle speed detection value V is equal to or higher than the 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. .

Next, in step S4, the rear wheel target steering angle θ _RT and the target rotation of the electric motor 16 which are stored in advance in the memory, for example, are stored based on the rear wheel target steering angle θ _RT calculated in step S3. The target motor rotation angle θ _MT of the electric motor 16 is calculated by referring to the storage table showing the relationship with the angle θ _M , then the process proceeds to step S5, and the current motor rotation angle θ _MP stored in the memory is calculated. Then, the process proceeds to step S6, the current motor rotation angle θ _MP is subtracted from the target motor rotation angle θ _MT to calculate the deviation ε between the two, and then the process proceeds to step S7.

In step S7, in order to perform the PID control, the target current value I _T is calculated by performing the calculation of the following equation (2) based on the deviation ε, and this is updated and stored in a predetermined storage area of the memory. To 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 is a Laplace operator.

Then, the process proceeds to step S8, and it is determined whether or not the left cutting is performed. This judgment 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) If it is, it is judged to be left-turned and the process proceeds to step S9, the rotation direction signal SD is set to a logical value "1" indicating left-turning, and then the process proceeds to step S11, where θ _MK (n) ≤ θ _MT (n If it is -1), it is judged to be right-turning and the process proceeds to step S10,
After the turning direction signal SD is set to the logical value "0" indicating right turn, the process proceeds to step S11.

[0038] 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 sets the set value T _S for the sensor abnormality determination, which will be described later, in the steering angle reading process of FIGS. 4 and 5 every predetermined time (for example, 10 msc).
Execute with less than the time difference.

In the steering angle reading process of FIG. 4, first, in step S21, the steering angle detection pulse signal P1 of the first steering angle sensor 22 is read, and then the process goes to step S22 to read the detection pulse signal P1. It is determined whether the logical value is "0". If the logical value is "1", step S2 is performed.
3, the state of the detection pulse signal P1 is updated and stored in the previous value storage area formed in the memory, and then the timer interrupt processing is ended to return to the main program. When the logical value is "0", step S24 is performed. Move to.

In step S24, it is determined whether or not the previous value of the detection pulse signal P1 was the logical value "1",
When the previous value is also the logical value "0", it is determined that the logical value "0" is continuing, and the timer interrupt process is terminated as it is. When the previous value is the logical value "1", the logical value "1" is set. It is judged that it is the time of the signal falling when the logic value is inverted from "" to the logical value "0", and the process proceeds to step S25.

In step S25, the current time T _P1 of the built-in timepiece is updated and stored in the first steering angle detection pulse signal time storage area formed in the memory, and then step S26.
Then, the process of starting the steering angle calculation process, which will be described later, is performed, the timer interrupt process is terminated, and the process returns to the main program.

In the steering angle reading process of FIG. 5, the steering angle detection pulse signal P2 of the second steering angle sensor 23 is first read in step S31, and then the detection pulse signal P2 is read in step S32. Is a logical value "0", and if it is a logical value "1", step S
After shifting to 33, the state of the detection pulse signal P2 is updated and stored in the previous value storage area formed in the memory, and then the timer interrupt processing is ended and the main program is returned to the logical value "0".
If so, the process proceeds to step S34.

In step S34, it is determined whether or not the previous value of the detection pulse signal P1 was the logical value "1",
When the previous value is also the logical value "0", it is determined that the logical value "0" is continuing, and the timer interrupt process is terminated as it is. When the previous value is the logical value "1", the logical value "1" is set. It is determined that the signal has fallen from "" to the logical value "0", and the process proceeds to step S35.

In step S35, the current time T _P2 of the built-in timepiece is updated and stored in the second steering angle detection pulse signal time storage area formed in the memory, and then step S36.
6 and the steering angle calculation process shown in FIG. 6, which will be described later, is started, the timer interrupt process is terminated, and the process returns to the main program.

In the initial state in which the arithmetic operation is started by the rear wheel steering controller 30 with the key switch turned on, the first steering angle detection pulse signal time storage area and the second steering angle detection pulse signal time storage area are obtained. In, a time having a time difference of a set value T _S or more, which will be described later, is stored as an initial value.

When the steering angle calculation process activation process of FIGS. 4 and 5 is executed, the steering angle calculation process shown in FIG. 6 is started. This steering angle calculation process is performed in step S41.
Then, it is determined whether or not the state of the steering angle detection pulse signal P1 stored in the previous value storage area is the logical value "0". If this is the logical value "0", the process proceeds to step S42, It is determined whether or not the state of the steering angle detection pulse signal P2 stored in the value storage area is the logical value "0", and when it is the logical value "0", it is determined that the steering wheel is in the left-turning state and the step S43. Steering angle detection value θ stored in the counter area representing the steering angle formed in the memory
_After counting up _D by "1", the timer interrupt processing is terminated and the program returns to the main program.

On the other hand, when the result of determination in step S41 is that the steering angle detection pulse signal P1 has the logical value "1", the process proceeds to step S44 and the steering angle detection pulse signal P2 is reached.
Of the logical value "1" is determined. If the logical value is "0", it is determined that the state is the left cut state, and the process proceeds to step S43. If the logical value is "1", the state is right. When it is determined that the steering wheel is in the off state, the process proceeds to step S45, and the steering angle detection value θ stored in the counter area is stored.
_After counting down _D by "1", the timer interrupt processing is terminated and the process returns to the main program. Also, when the result of the determination in step S42 is that the steering angle detection pulse signal P2 is the logical value "1", When it is determined that the cutting state is set, the process proceeds to step S45.

Further, the rear wheel steering controller 30 is
Executing a sensor abnormality determination processing in FIG 7 at predetermined time intervals (e.g. 10 ms e c). The sensor abnormality determination process of Fig. 7, first, at step S51, the first and second steering rudder detection pulse signal time storage first and second stored in the area
The falling times T _P1 and T _P2 of the pulse are read, and then the process proceeds to step S52 to calculate the pulse time difference A according to the following equation (3).

A = | T _P1 -T _P2 | (3) Then, the process proceeds to step S53, and it is determined whether or not the calculated pulse time difference A is less than a preset set value T _S. To do. This determination is based on the first steering angle detection pulse signal P1.
When are those abnormal short circuit determining whether or not generated between the second steering angle detection pulse signal P2, when it is A <T _S, the first and second of the steering angle sensor 22, 23 It is determined that a short circuit abnormality has occurred between the steering angle detection pulse signals P1 and P2 of No. 2 and the process proceeds to step S54, and after performing the abnormality detection process for forcibly ending the rear wheel steering process of FIG. When the processing is ended and A ≧ T _S , it is determined that the steering angle sensors 22 and 23 are normal, and the timer interrupt processing is ended as it is to return to the main program.

The set value T _S is selected to be smaller than the time difference between the steering angle detection pulse signals P1 and P2 when the steering wheel 1 is steered as much as possible.

Furthermore, the rear wheel steering controller 30
Is the steering angle performance of FIG. 8 every predetermined time (for example, 10 msc).
Perform arithmetic processing. This steering angle calculation process is performed by first
At step S61, memory is calculated in the previous interrupt cycle.
Moving as a pseudo neutral position stored in a predetermined storage area
Dynamic average θ _CAAnd the value of the original neutral position θ_CRead, next
Then, the process proceeds to step S62 and the steering angle calculation process of FIG.
Steering angle θ_DRead in.

Next, in step S63, the moving average value θ _CA is calculated by the calculation of the following equation (4), and this is updated and stored in the moving average value storage area of the memory. [theta] _CA = [theta] _{CA- [} theta] _C / 100 + [theta] _D / 100 (4) The calculation in step S63 corresponds to obtaining a moving average of 100 steering angles.

Next, in step S64, it is determined whether the neutral position detection signal PN of the neutral position sensor 24 is "1", and the neutral position detection signal PN is a logical value "1".
If it is, it is determined that the steering wheel 1 is at a substantially neutral position that represents a straight traveling state, and the moving average value θ _CA calculated in step S63 accurately represents the neutral position, and the process proceeds to step S65. Then, the moving average value θ _CA is set as the neutral position θ _C and updated and stored in a predetermined storage area of the memory, and then the process proceeds to step S66.

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

In step S66, the value obtained by subtracting the neutral position θ _C stored in the neutral position storage area of the memory from the steering angle θ _D read in step S62 is the front wheel steering angle θ _F
Is updated and stored in the front wheel steering angle storage area of the memory.

Here, if the front wheel steering angle θ _F is positive, it indicates that the steering wheel is turned left, and if it is negative, it is turned right. Therefore, when the vehicle now turns straight from the straight running state to the left turning state and both steering angle sensors 22 and 23 are normal, the steering angle sensor is turned in accordance with the left turning of the steering wheel 1. 22 and 23
As shown in FIG. 9, the second steering angle detection pulse signal P2 of the steering angle sensor 22 is output in a 90 ° phase advance with respect to the first steering angle detection pulse signal P1 of the steering angle sensor 22. .

Therefore, at time t ₁ in FIG. 9, the second steering angle detection pulse signal P2 changes from the logical value "1" to the logical value "0".
5, when the steering angle reading process of FIG. 5 is executed, the process proceeds from step S32 to step S34 to step S35, and the current time T _P2 at that time is set to the second value.
After being updated and stored in the steering angle detection pulse signal time storage area, the process proceeds to step S36 to start the steering angle calculation process of FIG. 6, and then proceeds to step S33 to store the second steering angle in the previous value storage region of the memory. The logical value "0", which is the state of the detection pulse signal P2, is updated and stored.

Therefore, when the processing of FIG. 5 is completed, the steering angle calculation processing of FIG. 6 is started, and at the time t ₁ , as shown in FIG. 9, the first steering angle detection pulse signal P1 is a logical value. Since it is "1", steps S41 to S44
When the logical value "0" is stored in the previous value storage area of the second steering angle detection pulse signal P2, it is determined that the vehicle is in the left-turning state, the process proceeds to step S43, and the counter is set to " By incrementing by 1 ", the steering angle detection value θ _D is incremented from the value corresponding to the neutral position θ _C.

On the other hand, when the steering angle calculation process of FIG. 8 is executed, the moving average value θ _CA of the steering angle is calculated based on the detected steering angle value θ _D and the neutral position θ _C. At this time, the neutral position sensor Since the neutral position detection signal PN of 24 is a logical value “1”, the calculated moving average value θ _CA is updated and stored in the neutral position storage area as the neutral position θ _C , and the steering angle detection value θ _{D is used as the} neutral position. The front wheel steering angle θ _F is calculated by subtracting θ _C , and this is updated and stored in the front wheel steering angle storage area.

Therefore, when the rear wheel steering process of FIG. 3 is executed, the rear wheel target steering angle θ _RT is calculated based on the front wheel steering angle θ _F , and the target motor rotation angle θ _MT is calculated based on this. The target motor rotation angle θ _MT and the current motor rotation angle θ _MP
The rear wheel steering control is performed by PID controlling the electric motor 16 of the rear wheel steering actuator 15 based on the deviation ε between

[0062] Then, the first steering angle detection pulse signal P1 at time t ₂ in FIG. 9 falls to the logic value "0" from logic "1", the steering angle reading process of FIG. 4 is executed immediately after the At this time, the current time T _P1 is updated and stored in the first steering angle detection pulse signal time storage area, and the logical value “0” is updated and stored in the previous value storage area, as in the above-described processing of FIG. To be done.

Therefore, when the steering angle calculation process of FIG. 6 is executed, the process proceeds from step S41 to step S42, and the second steering angle detection pulse signal P2 at this time has the logical value "0". , The steering angle detection value θ _D is incremented from the value corresponding to the neutral position θ _C by shifting to step S43 and incrementing the counter by “1”.

By executing the rear wheel steering process of FIG. 3 based on the detected steering angle value θ _D , the rear wheel steering control at the time of turning left is continued. In this way, the steering angle detection value θ _D is continuously counted up while the steering wheel 1 is left-turned, and when the steering wheel 1 is returned from the left turn state to the straight traveling state, the steering wheel 1 is turned right. As a result, the first and second steering angle detection pulse signals P1 and P2 output from the steering angle sensors 22 and 23 are changed to the second steering angle detection pulse signal P1 as shown in FIG. By advancing the phase by 90 ° with respect to the angle detection pulse signal P2, the steering angle detection value θ _D is counted down when the steering angle calculation process of FIG. 6 is executed.

When the neutral position signal PN of the neutral position sensor 24 becomes the logical value "1", the moving average value θ _CA is set as the neutral position θ _C. On the other hand, the sensor abnormality detecting process in FIG. 7 at predetermined time intervals is executed, in this case, since the steering angle sensor 22 and 23 are normal, the second steering angle detection pulse signal time in time t ₁ described above time difference a between the storage area update stored current time T _P2 and time t ₂ at a first steering angle detection pulse signal times the storage area update stored current time T _P1 will be greater than the set value T _S The timer interrupt process is ended as it is, and the steering angle calculation process and the rear wheel steering control process are continued.

However, when an abnormality occurs in which the steering angle sensors 22 and 23 are short-circuited while the steering wheel 1 is turned to the right, for example, a wired-and state occurs, and as shown in FIG. And the second steering angle detection pulse signals P1 and P2 have a pulse width of half and having the same phase only in the section where the logical value is "1" in the state of FIG. Become.

At this time, if the timer interruption processing of the steering angle reading processing for the steering angle sensor 22 of FIG. 4 is executed before the timer interruption processing for the steering angle reading processing of FIG. Whether to turn left or right, the steering angle reading process for the steering angle sensor 22 shown in FIG. 4 is always less than the set value T _S after the current time T _P1 is updated and stored in the first steering angle detection pulse signal time storage area. The steering angle reading process for the steering angle sensor 23 in FIG. 5 is executed, and the current time T _{P2 is} stored in the second steering angle detection pulse signal time storage area.
Will be updated and stored, and the time difference A between the current times T _P1 and T _P2 stored in both time storage areas matches the execution interval of the timer interrupt process of FIGS. 4 and 5.

Therefore, since the time difference A is determined to be less than the set value T _{S in} step S53, it is possible to reliably detect the occurrence of the short-circuit abnormality of the steering angle sensor, and in response to this, the process proceeds to step S54. Then, the abnormality detection process is executed, the rear wheel steering control process is stopped, and the steering detection value θ
_It is possible to reliably prevent the influence of the rear wheel steering control due to the deviation of _D from the actual steering angle.

That is, when a short circuit abnormality occurs in the steering angle sensors 22 and 23, the steering angle detection pulse signals P1 and P2 are read at a predetermined cycle in the steering angle reading process of FIGS. When the signals P1 and P2 have the logical value "0", it is determined that the pulse signal falls when the previous value has the logical value "1". When the steering angle calculation processing of FIG. 6 is sequentially executed in the order of execution of the steering angle reading processing of FIGS.
At the time point when the fall of the first steering angle detection pulse signal P1 of the steering angle sensor 22 is detected in the steering angle reading process of FIG. 2, the second steering angle detection pulse signal P2 of the steering angle sensor 23 also falls, from step S41 when the steering angle computing process in 6 is performed the process proceeds to step S43 through step S44, the counter counts up, the delayed in Figure 5 the steering angle read processing a second is executed which since falls in the first steering angle detection pulse signal P1 at the time of detecting the fall of the steering angle detection pulse signal P2, the step S4 4 from step S41 when the steering angle computing process in FIG. 6 is executed After that, the process proceeds to step S43 and the counter is incremented.

Therefore, when a short circuit abnormality occurs between the steering angle sensors 22 and 23, the steering angle detection value θ _D will continue to monotonically count up regardless of whether the steering wheel 1 is turned left or right. Although an actual steering angle change due to steering of the steering wheel 1 and a deviation that increases with the passage of steering time will occur, which will greatly affect the rear wheel steering control.
As described above, when a short circuit abnormality occurs between the steering angle sensors 22 and 23, it is possible to immediately detect the short circuit abnormality and stop the rear wheel steering control, so that the influence on the rear wheel steering control is minimized. You can keep it to the limit.

In the first embodiment, the case where the time difference at the time of the fall of the steering angle detection pulse signals P1 and P2 from the logical value "1" to the logical value "0" is detected has been described. However, the present invention is not limited to this, and the logical values of the steering angle detection pulse signals P1 and P2 are “0”.
It is needless to say that the time difference at the time of rising from the to logical value "1" may be detected.

Next, a second embodiment of the present invention will be described with reference to FIGS.
14 will be described. In the second embodiment, instead of storing the time at the time when the steering angle detection pulse signals P1 and P2 change in the first embodiment, as shown in FIG.
The time elapsed from the time when the change in the steering angle detection pulse signal P1 is detected in the steering angle reading process of FIG. 5 to the time when the change in the steering angle detection pulse signal P2 is detected in the steering angle reading process in FIG. A short circuit abnormality between the steering angle sensors 22 and 23 is detected.

In the second embodiment, as shown in FIG. 12, the steering angle reading process corresponding to FIG.
The time storing process in step S25 is replaced with step S71 in which the timer starting process of clearing and starting the timer that counts up every predetermined clock pulse is performed, and the steering angle reading process corresponding to FIG. As shown in FIG. 13, the time determination process in step 35 of FIG. 5 is step S72 of performing the timer stop process for stopping the timer and the abnormality determination value formed in the memory as the abnormality determination value A at that time. This is replaced with step S73 for performing a storage process of updating and storing in the storage area.

In the sensor abnormality detection process corresponding to FIG. 7 described above, as shown in FIG. 14, the abnormality determination value A stored in the abnormality determination value storage area is read in step S74, and then the process proceeds to step S75. Then, it is determined whether or not the read abnormality determination value A is less than a preset setting value X. When A ≧ X, the steering angle sensors 22 and 2 are determined.
It is determined that the short circuit abnormality has not occurred between 3 and the timer interrupt processing is terminated and the main program is restored. When A <X, a short circuit abnormality occurs between the steering angle sensors 22 and 23. it is determined that there, so as to end the transition to the timer interrupt processing in step S76 to perform different <br/> normal detection processing in the same manner as step S54 of FIG. 7 in the first embodiment described above It is configured.

According to the second embodiment, when the steering angle sensors 22 and 23 are normal, the steering wheel 1
Since the steering angle detection pulse signals P1 and P2 shown in FIG. 9 or 10 have a phase difference of 90 ° or 270 ° when the vehicle is turned left or right, the first steering angle detection pulse in the steering angle reading process of FIG. From the time when the falling of the signal P1 is detected and the timer is started to the time when the falling of the second steering angle detection pulse signal P2 is detected by the steering angle reading processing of FIG. 13 and the timer is stopped. The abnormality determination value A, which is the count value of the timer, is larger than the set value X.

Therefore, when the sensor abnormality detection process of FIG. 7 is executed, the abnormality determination value A becomes a value larger than the set value X, so that no short circuit abnormality has occurred between the steering angle sensors 22 and 23. By deciding that, the timer interrupt process is ended and the process is returned to the main program, whereby the rear wheel steering control process based on the detected front wheel steering angle θ _F is normally executed.

However, when a short circuit abnormality occurs between the steering angle sensors 22 and 23, the first steering angle detection pulse signal P1 and the second steering angle detection pulse are generated as in the first embodiment. Since the signal P2 has the same phase and the same pulse width, the steering angle reading process of FIG. 12 detects the trailing edge of the first steering angle detection pulse signal P1 and starts the timer, and then the steering angle reading of FIG. The time until the timer is stopped when the falling of the second steering angle detection pulse signal P2 is detected in the processing is from when the steering angle reading processing of FIG. 12 is started to when the steering angle reading processing of FIG. 13 is started. The time is substantially equal to the time of, and the abnormality determination value A, which is the count value of the timer, is less than the set value X.

Therefore, when the sensor abnormality detection process of FIG. 14 is executed, steps S75 to S76 are executed.
And the abnormality detection process is executed, it is possible to reliably detect a short circuit abnormality between the steering angle sensors 22 and 23, and the rear wheel steering control process is performed similarly to the first embodiment described above. It is possible to reliably suppress the influence on the rear wheel steering control that is caused by the fact that the front wheel steering angle θ _F is deviated from the actual steering angle due to the short-circuit abnormality between the steering angle sensors 22 and 23.

In the second embodiment, as in the first embodiment, the steering angle detection pulse signal P1 is used instead of detecting the falling points of the steering angle detection pulse signals P1 and P2. As a matter of course, the rising time points of P2 and P2 may be detected.

In addition, in the above-mentioned first and second embodiments
The neutral position sensor 24 is provided to correct the neutral position.
Although the case has been described, this can be omitted to detect the steering angle.
Value θ _DThe moving average value of the
You may set it.

[Brief description of drawings]

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

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

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

FIG. 4 is a flowchart showing an example of a steering angle reading processing procedure for the first steering angle sensor of the rear wheel steering controller.

FIG. 5 is a flowchart showing an example of a steering angle reading processing procedure for a second steering angle sensor of the rear wheel steering controller.

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

FIG. 7 is a flowchart illustrating an example of a sensor abnormality detection processing procedure of the rear wheel steering controller.

FIG. 8 is a flowchart showing an example of a front wheel steering angle calculation processing procedure of a rear wheel steering controller.

FIG. 9 is a waveform diagram showing first and second steering angle detection pulse signals in a left turning state.

FIG. 10 is a waveform diagram showing first and second steering angle detection pulse signals in a right turning state.

FIG. 11 is a waveform diagram showing first and second steering angle detection pulse signals when a short circuit abnormality occurs between the first and second steering angle sensors.

FIG. 12 is a flowchart showing an example of a steering angle reading processing procedure for the first steering angle sensor of the rear wheel steering controller in the second embodiment.

FIG. 13 is a flowchart showing an example of a steering angle reading processing procedure for a second steering angle sensor of the rear wheel steering controller in the second embodiment.

FIG. 14 is a flowchart illustrating an example of a sensor abnormality detection processing procedure of the rear wheel steering controller according to the second embodiment.

[Explanation of symbols]

1 steering wheel 2 steering shaft 6FL, 6FR front wheels 6RL, 6RR rear wheels 15 Rear wheel side actuator 16 Electric motor 20 Steering angle detection mechanism 21 Vehicle speed sensor 22 First steering angle sensor 23 Second steering angle sensor 24 Neutral position sensor 26 Rotation angle measurement circuit 27 Motor drive circuit 30 Rear wheel steering controller

Continuation of front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) G01B 21/00 B62D 6/00

Claims (3)

(57) [Claims] 1. A steering angle detection device for detecting a steering angle in a steering system of a vehicle, comprising: a plurality of steering angle sensors for outputting steering angle detection pulse signals having different phases according to changes in the steering angle of the steering system; Phase difference detection means for detecting a phase difference between the steering angle detection pulse signals of the plurality of steering angle sensors, and the steering angle sensor is in a short circuit abnormality when the phase difference detected by the phase difference detection means is less than a set value. A steering angle detecting device comprising: a sensor abnormality detecting unit that determines that 2. The phase difference detecting means detects a value obtained by subtracting a change time of a steering angle detection pulse signal of another steering angle sensor from a change time of a steering angle detection pulse signal of another steering angle sensor as a phase difference. The steering angle detection device according to claim 1, wherein the steering angle detection device is configured to: 3. The phase difference detecting means detects, as a phase difference, a measurement time from a change time point of a steering angle detection pulse signal of one steering angle sensor to a change time point of a steering angle detection pulse signal of another steering angle sensor. The steering angle detection device according to claim 1, wherein the steering angle detection device is configured to: