JPH0715381B2 - Steering angle detector - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a steering angle detection device used for detecting a steering angle of an automobile, and more specifically, correcting a detection value according to a steering speed and a steering direction. The present invention relates to a steering angle detection device that improves the accuracy of operation.

(Prior Art) This type of steering angle detection device detects the steering angle by the steering operation of an automobile, and is, for example, the Nissan Service Weekly Report No. 491 (issued by Nissan Motor Co., Ltd. October 1983) III-. Those described on page 56 are known.

In this steering angle detecting device, a rotary plate having a slit is provided so as to rotate integrally with a steering shaft, and two sets of light, which pass through the slit of the rotary plate and are interrupted as the steering wheel rotates, are arranged in the rotational direction. The light receiving sensor receives the light, and the controller calculates the steering angle based on the light receiving signal that is output by the light receiving sensor and indicates whether or not the light is received. The received light signal is, for example, a rectangular pulse signal having a high potential H when receiving light, and is output to the controller. The controller determines the potential (signal level) of the light receiving signal output by one light receiving sensor in a predetermined cycle to calculate the frequency of the light receiving signal, detects the steering angle of the steering wheel from this frequency, and The steering direction of the steering wheel is determined based on the phase difference between the light receiving signals output by the light receiving sensors.

(Problems to be Solved by the Invention) However, in such a conventional steering angle detection device, the controller determines the signal level of the light reception signal output by the light reception sensor in a predetermined cycle to calculate the frequency, and Since the steering angle of the steering wheel is detected based on the frequency of the received light signal, when the steering speed of the steering wheel increases and the cycle of the received light signal becomes shorter than the cycle of signal level determination by the controller, the controller determines the frequency of the received light signal. There is a problem in that the calculation cannot be performed accurately and the error of the steering angle detected based on this frequency becomes large. That is, in the case where the controller determines the signal level (high potential, low potential) of one light receiving signal in each predetermined determination cycle, after the determination of a certain first floor and within the determination cycle until the next determination is performed. Even if the steered steering is performed and the received light signal level changes excessively, it cannot be grasped at all, and as a result, the accurate cycle of the received light signal cannot be known, and the steering angle can be accurately calculated. It will disappear.

On the other hand, it is conceivable to change the determination cycle according to the steering speed, for example, but the processing for that is complicated and the cost is high. Also, just because the steering angle can be strictly detected during an extremely sudden steering does not mean that the power steering device can immediately respond to it.
It is extremely uneconomical.

Therefore, an object of the present invention is to provide a low-cost steering angle detecting device capable of detecting a steering angle with sufficient detection accuracy.

(Means for Solving the Problem) In order to achieve the above object, a steering angle detection device according to the present invention, as shown in FIG. 1, has a rotating body 11 for transmitting rotation of a steering wheel and a coaxial body for the rotating body 11. A plurality of slits 12 that are provided so as to rotate integrally and integrally and that can transmit or reflect light.
a (pattern) is a rotating disk 12 formed at a predetermined interval in the circumferential direction, and a light emitting element 13a and a light emitting element 13a which are arranged at a predetermined interval corresponding to the circumferential interval of the slit 12a and emit light. Two photo couplers 13 each having a light receiving element 13b into which the emitted light enters through the slit 12a, and outputting first and second received light digital signals whose signal levels change depending on whether the light receiving element 13b receives light or not. , Direction determination for determining the rotation direction of the rotating body 11 based on the signal level of one of the first and second received light digital signals output from the two photocouplers 13 when the signal level of the other changes. Means 15, a rotation direction storage means 16 for storing the direction discriminated by the direction discriminating means 15, and a rotational speed of the rotating body 11 depending on whether or not both the two received light digital signals have changed within the predetermined period. The speed discriminating means 17 for discriminating whether or not the velocity exceeds a predetermined velocity, and when one of the first and second light receiving digital signals changes within the predetermined period, the circumferential intervals of the plurality of patterns are determined. A rotation angle calculation means 19 for calculating a rotation angle of the rotating body 11 by adding or subtracting a corresponding predetermined unit angle value according to the rotation direction of the rotating body 11 determined by the direction determining means, and the speed. Based on the output signal of the determination means 17, when the rotation speed of the rotating body 11 exceeds a predetermined speed, the angle value is added or subtracted in the same direction as the rotation direction stored in the rotation direction storage means 16. The correction means 18 is provided.

(Operation) In the present invention, when the signal level of one of the first and second received light digital signals changes, the direction determining means 15 determines the rotational direction of the rotating body 11 from the other signal level, The determined direction is stored in the rotation direction storage means 16. Further, the speed discriminating means 17 determines whether or not the rotation speed of the rotating body 11 exceeds the predetermined speed depending on whether or not the first and second received light digital signals output from the two photocouplers both change within the predetermined period. Is determined. Then, when the rotation speed of the rotating body 11 is within a normal range that does not exceed a predetermined speed, the rotation angle calculation means 19 is, for each of the predetermined cycles, a predetermined unit angle value corresponding to the circumferential interval of the plurality of patterns. Is added or subtracted according to the rotation direction of the rotating body 11 determined by the direction determining means 15 to calculate the rotation angle of the rotating body 11. On the other hand, when the rotation speed of the rotating body 11 exceeds the predetermined speed due to the sudden steering, both the first and second received light digital signals may change the signal level within the cycle of the signal level determination by the controller. In this case, however, the speed discriminating means 17 discriminates that the rotational speed of the rotating body 11 has exceeded the predetermined speed, and the correcting means 18 is operated based on the output signal of the speed discriminating means 17, whereby the rotational direction storing means. The angle values are added in the same direction as the rotation direction stored in 16. That is, in calculating the rotation angle, in addition to the addition or subtraction processing of the unit angle value by the rotation angle calculation means 19, the correction processing is performed by the correction means 18 so as to additionally add or subtract the unit angle value. . Therefore, when the signal level of only one of the first and second received light digital signals changes within the predetermined cycle due to normal steering, and when the signal level of the steered steering exceeding the predetermined speed causes the first signal within the predetermined cycle.
In any case where both the second light receiving digital signal and the second light receiving digital signal change, it is not necessary to change the rotation angle calculation cycle of the rotation angle calculation means 19 and the determination cycle of the speed determination means 17, and simple processing is possible. Since (program) is sufficient, cost can be reduced and accurate steering angle can be detected.

(Example) Hereinafter, the present invention will be described with reference to the drawings.

2 to 7 are views showing an embodiment of the steering angle detecting device according to the present invention.

First, the configuration will be described.

In FIG. 2, reference numeral 21 denotes a steering shaft (rotating body) that is rotatably supported by the steering column and that transmits the rotation of a steering wheel (not shown) to the steering wheel side.
Reference numeral 22 is a rotating disk mounted coaxially and integrally with the steering shaft 21. A plurality of slits 22a are formed in the rotating disc 22 as a plurality of patterns capable of transmitting light at predetermined intervals P (equal angular intervals) in the circumferential direction, and the slits 22a of the rotating disc 22 are formed in the steering column at the slits 22a. Correspondingly, two (plural) photocouplers 23, 24 are attached. These photocouplers 23, 24 are arranged in the same direction as the arrangement direction of the slits 22a, that is, the rotary disc
1/4 of the predetermined interval p between the above-mentioned slits 22a in the circumferential direction of
The light emitting diodes 23a and 24a (light emitting elements) which emit light and are arranged at predetermined intervals (p / 4) (however, (n + 1/4) is also possible, n: integer) The slits 22a of the rotating disk 22 direct the light emitted from 23a and 24a.
And phototransistors 23b and 24b (light receiving elements) that receive light via. These light emitting diodes 23a, 2
The 4a and the phototransistors 23b and 24b are connected to a controller 25 equipped with a one-chip microcomputer or the like, and each phototransistor 23b and 24b has a high potential H when receiving light, that is, a rectangle whose signal level changes depending on whether light is received or not. Pulsed first and second received light digital signals A, B
(See FIGS. 3 to 6) are output.

The signal levels (high potential H and low potential L) of the first and second received light digital signals A and B output by the two photocouplers 23 and 24 can be determined in a predetermined cycle, and the directions are determined accordingly. It has the function of the direction determination means and the function of the rotation direction storage means. Due to the function of the direction determining means, the controller 25 changes the signal level of either one of the received light digital signals A and B output by the two photocouplers 23 and 24 based on the signal level of the other, based on the other signal level. The rotation direction of the is determined, and the determined rotation direction is the function of the rotation direction storage means (flag FLAG described later).
Memorized by. Further, the controller 25 has a function of a rotation angle calculation means, and the function of the rotation angle calculation means changes the signal level of at least one of the received light digital signals A and B within a cycle immediately before every predetermined cycle. If there is a change, a predetermined unit angle value corresponding to the circumferential interval p of the plurality of slits 22a (the ANGL which will be described later)
Value corresponding to one unit of E value) is added or subtracted according to the rotation direction stored by the function of the rotation direction storage means,
The rotation angle of the steering shaft 21 is calculated. Further, the controller 25 has the functions of the speed discriminating means and the correcting means, and by the function of the speed discriminating means, the first and second received light digital signals A,
It is determined whether or not the rotation speed of the steering shaft 21 exceeds a predetermined speed depending on whether both B (hereinafter, also simply referred to as light reception signals A and B) have changed, and the rotation speed of the steering shaft 21 exceeds the determination speed. Then, the function of the correction means adds the angle value in the same direction as the stored rotation direction. That is, when the steering speed exceeds a predetermined value, the controller 25 is configured to perform a correction process to increase a unit angle value to be added or subtracted as a rotation angle calculation means. The value is changed to twice the unit angle value (a value corresponding to twice one unit of the ANGLE value described later) (details will be described later).

Next, the operation will be described.

In this steering angle detecting device, when the steering shaft 21 is rotated by a steering operation, each photocoupler 23, 24 is emitted by each light emitting diode 23a, 24a along with the rotation of the rotating disk 22 that rotates integrally with the steering shaft 21. Light is intermittently incident on the phototransistors 23b and 24b through the slits 22a of the rotating disk 22, and as described above, when the phototransistors 23b and 24b receive light, the high potential H
Controller for receiving rectangular pulse light reception signals A and B having
Output to 25. As shown in FIGS. 3 to 6, the photocouplers 23 and 24 have slits 22a for the received light signals A and B.
The steering shaft 21 has a phase difference as shown in FIG. 3 and FIG. Has a phase difference as shown in FIGS. 4 and 6 when it is rotated counterclockwise. That is, the received light signals A and B
Shows a change in signal level as shown in a separate table depending on the rotation direction. Then, the controller 25 indicates the signal level (H or L) of the light receiving signals A and B at each of the predetermined cycles, as indicated by the broken lines with continuous numbers in FIGS. 3 to 6.
And based on that, the presence or absence of a change in the signal level of each of the signals A and B, the rotation direction of the steering shaft 21, and the determination as to whether or not the rotation speed exceeds a predetermined value are performed. After the determined rotation direction is stored by the flag setting, the unit angle value is added or subtracted according to the rotation direction to calculate the rotation angle, and the rotation speed of the steering shaft 21 exceeds a predetermined value. When the determination is made, correction is performed to change the angle value to be added or subtracted from the unit angle value to a value that is twice the same in the same direction as the stored rotation direction.

Hereinafter, the series of processes described above will be described in detail with reference to the flowchart of FIG.

This series of processes is repeatedly executed in the controller 25 at each of the predetermined cycles. First, at step P ₁ , the signal level of at least _one of the light receiving signals A and B is changed from the high potential H to the low potential L or from the low potential L to the high potential H. It is determined whether or not the potential has changed to H, that is, whether or not the steering shaft 21 has rotated. If the determination result is YES, the process proceeds to step P ₂ and N
If it is O, the processing of this time is ended as it is. Step P ₂
Now, it is determined whether or not the light receiving signal A, both the signal level of B changes, as a result advances to step P ₁₄ to be described later. If YES, the process proceeds to step P ₃ if NO. In other words, the step P ₂ is whether or not the cycle of the light receiving signals A and B is smaller than the cycle for determining the signal level of the light receiving signals A and B by the controller 25, that is, the steering shaft.
It is determined whether or not the rotation speed (steering speed) of the steering wheel 21 exceeds a predetermined value. If it is determined that the rotation speed of the steering shaft 21 exceeds the predetermined value, the process proceeds to step P ₁₄ .

In step P ₃ , it is determined whether or not the signal level of the light receiving signal A has changed, that is, whether only the signal level of the light receiving signal A has changed without changing the light receiving signal B, and if the result is YES. Go to step P ₄ , step NO if step P
Proceed to ₁₁ .

In step P ₄ , it is determined whether or not the signal level of the received light signal A has changed from the low potential L to the high potential H, and if the result is YES, the process proceeds to step P ₅ , and if NO, step P 4.
Go to ₆ .

In step P ₅ , it is determined whether or not the light receiving signal B is at the low potential L, and if the result is YES, the process proceeds to steps P ₇ and P ₉ one by one, together with the processing of adding “1” to the rotation angle ANGLE. to set the "phi" to flag FLAG, if NO, the the setting of "1" to the flag FLAG with subtraction of "1" from the rotation angle aNGLE sequentially willing to step P _8, P ₁₀ .

Similarly, in step P ₆ , it is determined whether or not the light receiving signal B is at the high potential H, and if the result is YES, steps P ₇ and P
Sequentially proceeds to _9, successively proceeds to step P _8, P ₁₀ if NO.
The steps P ₇ , P ₈ and the steps described below
In P ₁₅ and P ₁₆ , for convenience, the right rotation is set to be positive and the left rotation is set to be negative, and one unit of the value of the rotation angle ANGLE is the frequency corresponding to the interval p between the slits 22a of the rotary disc 22. Represent

Further, in step P ₁₁ , the received light signal B is at the low potential L.
From high to high potential H, and the result is YE
If S, proceed to Step P ₁₂ , and if NO, Step P ₁₃
Go to.

In step P _12, the light receiving signal A to determine whether the high potential H, the flag FLAG with calculation of sequential willing rotation angle ANGLE to step P _7, P ₉ If the result is YES
If it is NO, proceed to the steps P ₈ and P ₁₀ described above in order and calculate the rotation angle ANGLE and the flag FLAG.
Set.

Similarly, in step P _13, if the light receiving signal A is determined whether or not the low potential L, the result is YES step
Proceed to P ₇ and P ₉ sequentially, and if NO, proceed to steps P ₈ and P ₁₀ .

On the other hand, the set value of the flag FLAG at step P ₁₄ is "phi"
Or determines whether it is, as a result proceeds to step P ₁₅ If is YES, the process proceeds to step P ₁₆ if NO.

Performs addition processing of "2" to the rotation angle ANGLE in step P _15, also performs the subtraction processing of "2" to the rotation angle ANGLE in step P _16.

As described above, the series of processes from step P ₁ to step P ₁₆ described above is repeatedly executed.

Processing from step P ₃ as described above until the step P ₁₃ is within the normal steering speed range the rotational speed of the steering shaft 21 is equal to or less than a predetermined value, the process for calculating the rotation angle to determine the direction of rotation It is shown. More specifically, as shown in FIGS. 3 and 4, in the region where the rotation speed of the steering shaft 21 is equal to or lower than a predetermined speed, the signal level changes of the light receiving signals A and B are discriminated and based on the separate table. The rotation angle of the steering shaft 21 is determined and the rotation angle is calculated. That is, for example, when the steering shaft 21 rotates to the right, as shown in FIG.
The signal level of is determined, and similarly, as shown in FIG.
When the steering shaft 21 rotates counterclockwise, the signal levels of the received light signals A and B are determined at the time of the determination in the drawing, and whether or not the signal levels of the signals A and B have changed during each determination, that is, within the predetermined period. Check
The rotation angle of the steering shaft 21 from the reference position is calculated by adding or subtracting the ANGLE value according to the changed signal number and the rotation direction of the steering shaft 21.

On the other hand, the processing from step P ₁₄ to step P ₁₆ described above is processing for correcting according to the rotation direction when the steering shaft 21 rotates at a high speed and the two received light signals A and B both change. Is. That is, as shown in FIG. 5, when the steering shaft 21 rotates to the right at a high rotational speed, a change in the signal levels of both the light receiving signals A and B is detected at the time of the determination in the drawing, and the set value of the flag FLAG (memory) is stored. By grasping that the steering shaft 21 is rotating to the right from the rotation direction), it is estimated that the steering shaft 21 has rotated to the right by a larger angle within a predetermined period, and the angle value to be added is calculated correspondingly. Correction is made to a value (“+2”) that is twice the unit angle value (“+1”) in the normal steering speed range. Further, as shown in FIG. 6, when the steering shaft 21 rotates counterclockwise at a high rotation speed, the change in both the light receiving signals A and B is detected at the time of the determination in the figure, and the steering shaft 21 is moved to the left from the flag FLAG. By grasping that it is rotating, it is estimated that the steering shaft 21 has rotated counterclockwise by a larger angle within the predetermined period, and the angle value to be subtracted from the ANGLE value correspondingly is the unit for the normal steering speed range. Angle value ("-
The value is corrected to double the value of "1") ("-2"), that is, ANGLE ± 1 is processed within the normal steering speed range, whereas normal addition is applied to the signal level change of one signal. Alternatively, the error amount is corrected by processing ANGLE ± 2 so as to add or subtract one unit of ANGLE whose rotation speed is not calculated in the subtraction process.

As described above, in the steering angle detection device of the present embodiment,
When the rotation speed of the steering shaft 21 becomes equal to or higher than a predetermined speed due to the abrupt steering, both the first and second received light digital signals A and B are within the cycle (predetermined cycle) of the signal level determination by the controller 25. Level changes,
This is detected by the controller 25 as a speed determination means, and it is determined that the rotation speed of the steering shaft 21 exceeds a predetermined value, and the controller 25 is determined based on the determination result.
The flag FLAG is activated by the function of correcting
The angle value added or subtracted during the calculation of the rotation angle is the unit angle value (“+
The value (“+2” or “−2”) is doubled to 1 ”or“ −1 ”. Therefore, the first and second received light digital signals A, Either when the signal level of only one of the B signals changes, or when both the first and second received light digital signals A and B change their levels within the predetermined period due to sudden steering at a predetermined speed or higher. In this case, a sufficient steering angle detection accuracy can be obtained, and since the above correction is executed without changing the steering angle calculation period and the speed determination period, a simple program can be used. It only needs to be added, and the processing is simpler than in the case where the measurement time is changed, and the device can be made at low cost.

Incidentally, in the present embodiment, the pattern on the rotating disk was a slit capable of transmitting light, but the pattern is not limited to this, it is a mirror-like reflective pattern, to reflect the light emitted by the light emitting element, The light receiving element may receive it.

(Effects of the Invention) As described above, according to the steering angle detection device of the present invention, both the first and second received light digital signals have the same signal level when the rotation speed of the rotating body exceeds the predetermined speed. The signal level of the first and second received light digital signals is discriminated with a changeable time as a predetermined cycle, and based on the discrimination result, the presence or absence of rotation of the rotating body (signal level change) and the rotational direction are discriminated. While remembering the rotation direction,
It is determined whether or not the rotation speed exceeds a predetermined value, and if the rotation speed of the rotating body is within a normal range that does not exceed the predetermined speed, a predetermined value corresponding to the circumferential intervals of the plurality of patterns is provided at each of the predetermined cycles. The unit angle value of is added or subtracted according to the rotation direction discriminated by the direction discriminating means to calculate the rotation angle of the rotating body. On the other hand, the rotation speed of the rotating body exceeds the predetermined speed due to the sudden steering. In this case, it is determined that the rotation speed of the rotating body has exceeded the predetermined speed because both the first and second received light digital signals change the signal level within the predetermined period, and the rotation speed of the rotating body is stored based on the speed determination result. Since the correction is performed by increasing the addition or subtraction amount during the rotation angle calculation by adding the angle values in the same direction as the rotation direction in which the rotation angle is present, one light reception digital signal is determined at predetermined intervals. Steering rotation exceeding a predetermined speed, which cannot be grasped by determining the signal level, can be grasped from the signal level change of two light receiving digital signals having a predetermined phase, and the error can be corrected, and the angle can be corrected with sufficient accuracy. Detection can be performed.

Further, since it is not necessary to change the rotation angle calculation cycle by the rotation angle calculation means and the determination cycle of the speed determination means,
Only a simple processing means is required, and the cost can be reduced.

[Brief description of drawings]

FIG. 1 is a block diagram of a steering angle detecting device according to the present invention. 2 to 7 are views showing an embodiment of the steering angle detecting device according to the present invention. FIG. 2 is a schematic perspective view of the whole, and FIGS. 3 and 4 show a small steering speed. 5 and 6 are timing charts showing changes in the received light digital signal when the steering speed is high, and FIG. 7 shows the procedure of the steering angle detection process. It is a flowchart shown. 11 …… Rotating body, 12,22 …… Rotating disk, 12a, 22a …… Slit (pattern), 13,23,24 …… Photo coupler, 13a
...... Light emitting element, 13b ...... Light receiving element, 15 ...... Direction discriminating means, 16 ...... Rotation direction storing means, 17 ...... Speed discriminating means, 18
...... Correction means, 19 ...... Rotation angle calculation means, 21 ...... Steering shaft (rotating body), 23a, 24a ...... Light emitting diode (light emitting element), 23b, 24b ...... Phototransistor (light receiving element), 25 ...... Controller (direction discrimination means, speed discrimination means, rotation direction storage means, rotation angle calculation means, correction means).

Continuation of the front page (56) References JP-A-58-96253 (JP, A) JP-A-52-51959 (JP, A) Actually opened 59-149059 (JP, U) Actual-opened Sho 53-19261 (JP , U) Japanese Patent Publication No. 57-37029 (JP, B2)

Claims (1)

[Claims] 1. A rotating body that transmits the rotation of a steering wheel, and a rotating body that is coaxially and integrally rotated with the rotating body.
A rotating disk in which a plurality of patterns that can transmit or reflect light are formed at predetermined intervals in the circumferential direction, a light-emitting element that is provided at predetermined intervals corresponding to the circumferential interval of the pattern, and a light-emitting element that emits light. Two photocouplers for outputting first and second received light digital signals having a light receiving element through which the emitted light of the light enters through the pattern and the signal level of which changes depending on whether or not the light receiving element receives light. Direction discriminating means for discriminating the rotational direction of the rotating body based on the signal level of one of the first and second received digital signals output from the two photo couplers when the signal level changes, and the direction. The rotation direction storage means for storing the direction determined by the determination means, and the rotation speed of the rotating body depending on whether or not both the first and second received light digital signals have changed within a predetermined period. Speed determining means for determining whether or not the degree exceeds a predetermined speed, and when one of the first and second received light digital signals changes within the predetermined cycle, the plurality of patterns have circumferential intervals. A corresponding predetermined unit angle value is added or subtracted according to the rotation direction of the rotating body determined by the direction determining means to calculate a rotation angle of the rotating body, a rotation angle calculating means, and a speed determining means of the speed determining means. Correction means for adding the angle value in the same direction as the rotation direction stored in the rotation direction storage means when the rotation speed of the rotating body exceeds a predetermined speed based on the output signal. A characteristic steering angle detection device.